c programming structure assignment

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15.13 Structure Assignment

Assignment operating on a structure type copies the structure. The left and right operands must have the same type. Here is an example:

Notionally, assignment on a structure type works by copying each of the fields. Thus, if any of the fields has the const qualifier, that structure type does not allow assignment:

See Assignment Expressions .

When a structure type has a field which is an array, as here,

structure assigment such as r1 = r2 copies array fields’ contents just as it copies all the other fields.

This is the only way in C that you can operate on the whole contents of a array with one operation: when the array is contained in a struct . You can’t copy the contents of the data field as an array, because

would convert the array objects (as always) to pointers to the zeroth elements of the arrays (of type struct record * ), and the assignment would be invalid because the left operand is not an lvalue.

C Functions

C structures, c reference, c structures (structs).

Structures (also called structs) are a way to group several related variables into one place. Each variable in the structure is known as a member of the structure.

Unlike an array , a structure can contain many different data types (int, float, char, etc.).

Create a Structure

You can create a structure by using the struct keyword and declare each of its members inside curly braces:

To access the structure, you must create a variable of it.

Use the struct keyword inside the main() method, followed by the name of the structure and then the name of the structure variable:

Create a struct variable with the name "s1":

Access Structure Members

To access members of a structure, use the dot syntax ( . ):

Now you can easily create multiple structure variables with different values, using just one structure:

What About Strings in Structures?

Remember that strings in C are actually an array of characters, and unfortunately, you can't assign a value to an array like this:

An error will occur:

However, there is a solution for this! You can use the strcpy() function and assign the value to s1.myString , like this:

Simpler Syntax

You can also assign values to members of a structure variable at declaration time, in a single line.

Just insert the values in a comma-separated list inside curly braces {} . Note that you don't have to use the strcpy() function for string values with this technique:

Note: The order of the inserted values must match the order of the variable types declared in the structure (13 for int, 'B' for char, etc).

Copy Structures

You can also assign one structure to another.

In the following example, the values of s1 are copied to s2:

Modify Values

If you want to change/modify a value, you can use the dot syntax ( . ).

And to modify a string value, the strcpy() function is useful again:

Modifying values are especially useful when you copy structure values:

Ok, so, how are structures useful?

Imagine you have to write a program to store different information about Cars, such as brand, model, and year. What's great about structures is that you can create a single "Car template" and use it for every cars you make. See below for a real life example.

Real-Life Example

Use a structure to store different information about Cars:

C Exercises

Test yourself with exercises.

Fill in the missing part to create a Car structure:

Start the Exercise

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C Structure

Summary : in this tutorial, you will learn how to define a new type called C structure that allows you to wrap related variables with different types into a single entity.

Introduction to C structure

When you design software, it is important to choose an optimal way to represent the data that the program processes.

In simple cases, scalar variables and arrays are sufficient. However, in practical applications, you need a new form of variable that reflects the real-world data.

For example, you may want to reference an address that holds multiple fields including house number, street, zip code, state, and country.

To do it, C provides you with the structure type. A structure allows you to wrap related variables with different data types into a single variable.

Defining structure

To define a structure, you use the struct keyword. The following shows the syntax for defining a structure:

In this syntax:

First, use the struct keyword followed by the structure name.
Second, specify the elements of the structure including type and name. The elements of the structure are also called fields.

For example, the following defines the address structure:

The address structure includes house number, street name, city, state, zip code, and country.

Declaring structure variables

The above example defines the address structure without declaring any structure variables. C provides you with two ways to declare structure variables:

1) Declaring structure variables with the structure definition

The follownig shows the syntax for declaring structure variables with the structure definition:

In this syntax, you can omit the structure name like this:

For example, you can define the address structure and declare two structure variables:

In this example, the home_address and business_address are the structure variables. Alternatively, you can declare the structure variables as follows:

2) Declaring structure variables after defining the structure

The following shows the syntax for defining a structure and its variables:

In this syntax, you separate the structure definition from the variable declaration. For example:

Initializing structure variables

Like a regular variable, you can initialize a structure variable. The following example shows the syntax for initializing a structure variable:

For example, you can define a structure, declare a structure variable, and initialize the structure variable like this:

Accessing structure members

To access a structure member, you use the dot operator ( . ) as follows:

The following programm print out the fields of the address structure:

Structures that contain other structures

As mentioned earlier, a structure may contain another structure. For example, you can define the customer structure that contains the address structures:

In this example, the customer structure contains two members, shipping_address and billing_address which are also the structures.

When a structure contains a structure, you use the dot operator ( . ) to access the fields of the nested structure.

The following example defines the customer structure and variable ( john ). It then copies the string "San Fransisco" to the city of the shipping address of the customer:

Assigning a structure into another structure

C allows you to assign a structure to another by using the assignment operator ( = ):

Notice that some old C compilers may not support structure assignment. If this is the case, you have to assign each structure member individually.

The following program illustrates how to assign the business_address structure to the home_address structure using the assignment operator ( = ):

C structure type and the sizeof operator

To get the size of a structure, you cannot just simply add up the size of its fields. Instead, you use the sizeof() operator like the following example:

The sizeof() operator returns the size of a structure that is always bigger than the size of all the structure members.

The reason is that the compilers always need to pad the structure members so that each member can be accessed faster.

Structure shorthand with typedef keyword

The typedef keyword allows you to assign a new type name to an existing type. For example, you can assign a structure a new type name and use that type to declare a variable.

The following example uses the typedef keyword to define the address structure type:

The address is a new type now. So you can use it to declare variables like this:

The typedef makes your code less verbose and more concise.

C structure example

The following program illustrates how to use the structure to read the product information including name and quantity from the command line and display the total quantity of all the products:

To change the number of products that you want to enter, you need to change the SIZE constant.

A structure type combines multiple related fields with different types.
Use the struct keyword to define a structure.
Use the dot operator (.) to access the members of the structure.

Structures in C programming, need and use

Need of structures?
What is structure?
How to declare and define?
How to create structure object?
How to access structure members?
Example program

Structures in C, is an advance and most popular topic in C language. It facilitates you to design your custom data type . In this tutorial, we will learn about structures in C its need, how to declare, define and access structures.

Need of structures in C?

C has built in primitive and derrived data types . Still not all real world problems can be solved using those types. You need custom data type for different situations.

For example, if you need to store 100 student record that consist of name, age and mobile number. To code that you will create 3 array variables each of size 100 i.e. name[100] , age[100] , mobile[100] . For three fields in student record it say seem feasible to you. But, think how cumbersome it would be to manage student record with more than 10 fields, in separate variables for single student.

To overcome this we need a user defined data type. In this tutorial I am going to explain how easily we will deal with these situations using structures in C programming language.

What is structure in C?

Structure is a user defined data type. It is a collection of different data type, to create a new data type.

For example, You can define your custom type for storing student record containing name, age and mobile. Creating structure type will allow you to handle all properties (fields) of student with single variable, instead of handling it separately.

How to declare, define and access structure members?

To declare or define a structure, we use struct keyword. It is a reserved word in the C compiler. You must only use it for structure or its object declaration or definition.

Syntax to define a structure

Here, structure_name is name of our custom type. memberN_declaration is structure member i.e. variable declaration that structure will have.

Example to define a structure

Let us use our student example and define a structure to store student object.

Points to remember while structure definition

You must terminate structure definition with semicolon ; .

For example, following is an invalid structure definition.

You can define a structure anywhere like global scope (accessible by all functions) or local scope (accessible by particular function).
Structure member definition may contain other structure type.

How to create structure object (structure variable)?

A data type is useless without variables. A data type defines various properties about data stored in memory. To use any type we must declare its variable. Hence, let us learn how to create our custom structure type objects also known as structure variable .

In C programming, there are two ways to declare a structure variable:

Along with structure definition
After structure definition

Declaration along with the structure definition

Out of two ways to declare structure variable. You can declare a structure variable along with structure before terminating the structure definition.

So, if you want to declare student type object along with student structure definition you can use this approach.

Declaration after structure definition

The other way to declare, gives you luxury to declare structure variable anywhere in program based on the structure scope. If structure is defined in global scope, we can declare its variable in main() function , any other functions and in the global section too.

For above example, if we want to declare its variable with name student1 , it will be declared as given below:

How to access structure members (data)?

You created structure and its variable. But since structure is a complex data type, you cannot assign any value directly to it using assignment operator . You must assign data to individual structure members separately.

C supports two operators to access structure members, using a structure variable.

Dot/period operator .
Arrow operator ->

Dot/period operator (.) in C

Dot/period operator also known as member access operator. We use dot operator to access members of simple structure variable.

Read more about other operators in C programming language .

Arrow operator (->) in C

Since structure is a user defined type and you can have pointers to any type. Hence, you may also create pointers to structure.

In C language it is illegal to access a structure member from a pointer to structure variable using dot operator. We use arrow operator -> to access structure member from pointer to structure.

Example program to demonstrate declare, define and access structure members

In this example, we will declare a structure type, create structure object and access structure members. I will show how to use both dot and arrow operator to access structure members.

Happy coding 😉

Learn C practically and Get Certified .

C Fundamentals

C Variables, Constants and Literals
C Data Types
C Input Output (I/O)
C Programming Operators

C Flow Control

C if...else Statement
C while and do...while Loop
C break and continue
C switch Statement
C goto Statement
C Functions
C User-defined functions
Types of User-defined Functions in C Programming
C Recursion
C Storage Class

C Programming Arrays

C Multidimensional Arrays
Pass arrays to a function in C

C Programming Pointers

Relationship Between Arrays and Pointers
C Pass Addresses and Pointers

C Dynamic Memory Allocation

C Array and Pointer Examples
C Programming Strings
String Manipulations In C Programming Using Library Functions
String Examples in C Programming

C Structure and Union

C structs and pointers.

C Structure and Function

C Programming Files

C File Handling

C Files Examples

C Additional Topics

C Keywords and Identifiers
C Precedence And Associativity Of Operators
C Bitwise Operators
C Preprocessor and Macros
C Standard Library Functions

C Tutorials

Store Data in Structures Dynamically
C Struct Examples
Store Information of Students Using Structure

Before you learn about how pointers can be used with structs, be sure to check these tutorials:

C Pointers to struct

Here's how you can create pointers to structs.

Here, ptr is a pointer to struct .

Example: Access members using Pointer

To access members of a structure using pointers, we use the -> operator.

In this example, the address of person1 is stored in the personPtr pointer using personPtr = &person1; .

Now, you can access the members of person1 using the personPtr pointer.

By the way,

personPtr->age is equivalent to (*personPtr).age
personPtr->weight is equivalent to (*personPtr).weight
Dynamic memory allocation of structs

Before you proceed this section, we recommend you to check C dynamic memory allocation .

Sometimes, the number of struct variables you declared may be insufficient. You may need to allocate memory during run-time. Here's how you can achieve this in C programming.

Example: Dynamic memory allocation of structs

When you run the program, the output will be:

In the above example, n number of struct variables are created where n is entered by the user.

To allocate the memory for n number of struct person , we used,

Then, we used the ptr pointer to access elements of person .

Example: Access struct members using pointers

Sorry about that.

Structures in C

A structure in C is a derived or user-defined data type. We use the keyword struct to define a custom data type that groups together the elements of different types. The difference between an array and a structure is that an array is a homogenous collection of similar types, whereas a structure can have elements of different types stored adjacently and identified by a name.

We are often required to work with values of different data types having certain relationships among them. For example, a book is described by its title (string), author (string), price (double), number of pages (integer), etc. Instead of using four different variables, these values can be stored in a single struct variable.

Declare (Create) a Structure

You can create (declare) a structure by using the "struct" keyword followed by the structure_tag (structure name) and declare all of the members of the structure inside the curly braces along with their data types.

To define a structure, you must use the struct statement. The struct statement defines a new data type, with more than one member.

Syntax of Structure Declaration

The format (syntax) to declare a structure is as follows −

The structure tag is optional and each member definition is a normal variable definition, such as "int i;" or "float f;" or any other valid variable definition.

At the end of the structure's definition, before the final semicolon, you can specify one or more structure variables but it is optional .

In the following example we are declaring a structure for Book to store the details of a Book −

Here, we declared the structure variable book1 at the end of the structure definition. However, you can do it separately in a different statement.

Structure Variable Declaration

To access and manipulate the members of the structure, you need to declare its variable first. To declare a structure variable, write the structure name along with the "struct" keyword followed by the name of the structure variable. This structure variable will be used to access and manipulate the structure members.

The following statement demonstrates how to declare (create) a structure variable

Usually, a structure is declared before the first function is defined in the program, after the include statements. That way, the derived type can be used for declaring its variable inside any function.

Structure Initialization

The initialization of a struct variable is done by placing the value of each element inside curly brackets.

The following statement demonstrates the initialization of structure

Accessing the Structure Members

To access the members of a structure, first, you need to declare a structure variable and then use the dot (.) operator along with the structure variable.

The four elements of the struct variable book1 are accessed with the dot (.) operator . Hence, "book1.title" refers to the title element, "book1.author" is the author name, "book1.price" is the price, "book1.pages" is the fourth element (number of pages).

Take a look at the following example −

Run the code and check its output −

In the above program, we will make a small modification. Here, we will put the type definition and the variable declaration together, like this −

Note that if you a declare a struct variable in this way, then you cannot initialize it with curly brackets. Instead, the elements need to be assigned individually.

When you execute this code, it will produce the following output −

Copying Structures

The assignment (=) operator can be used to copy a structure directly. You can also use the assignment operator (=) to assign the value of the member of one structure to another.

Let's have two struct book variables, book1 and book2 . The variable book1 is initialized with declaration, and we wish to assign the same values of its elements to that of book2 .

We can assign individual elements as follows −

Note the use of strcpy() function to assign the value to a string variable instead of using the "= operator".

You can also assign book1 to book2 so that all the elements of book1 are respectively assigned to the elements of book2. Take a look at the following program code −

Structures as Function Arguments

You can pass a structure as a function argument in the same way as you pass any other variable or pointer.

Take a look at the following program code. It demonstrates how you can pass a structure as a function argument −

When the above code is compiled and executed, it produces the following result −

Pointers to Structures

You can define pointers to structures in the same way as you define pointers to any other variable.

Declaration of Pointer to a Structure

You can declare a pointer to a structure (or structure pointer) as follows −

Initialization of Pointer to a Structure

You can store the address of a structure variable in the above pointer variable struct_pointer . To find the address of a structure variable, place the '&' operator before the structure's name as follows −

Let's store the address of a struct variable in a struct pointer variable.

Accessing Members Using Pointer to a Structure

To access the members of a structure using a pointer to that structure, you must use the → operator as follows −

C defines the → symbol to be used with struct pointer as the indirection operator (also called struct dereference operator ). It helps to access the elements of the struct variable to which the pointer reference to.

In this example, strptr is a pointer to struct book book1 variable. Hence, strrptr→title returns the title, just like book1.title does.

When you run this code, it will produce the following output −

Note: The dot (.) operator is used to access the struct elements via the struct variable. To access the elements via its pointer, we must use the indirection (->) operator

A struct variable is like a normal variable of primary type, in the sense that you can have an array of struct, you can pass the struct variable to a function, as well as return a struct from a function.

You may have noted that you need to prefix "struct type" to the name of the variable or pointer at the time of declaration. This can be avoided by creating a shorthand notation with the help of typedef keyword, which we will explain in a subsequent chapter.

Structures are used in different applications such as databases, file management applications, and for handling complex data structures such as tree and linked lists.

Bit Fields allow the packing of data in a structure. This is especially useful when memory or data storage is at a premium. Typical examples include −

Packing several objects into a machine word, for example, 1-bit flags can be compacted.
Reading external file formats − non-standard file formats could be read in, for example, 9-bit integers.

Declaration

C allows us to do this in a structure definition by putting :bit length after the variable. For example −

Here, the packed_struct contains 6 members: Four 1 bit flags f1..f3, a 4-bit type and a 9-bit my_int.

C automatically packs the above bit fields as compactly as possible, provided that the maximum length of the field is less than or equal to the integer word length of the computer. If this is not the case, then some compilers may allow memory overlap for the fields while others would store the next field in the next word.

A man is valued by his works, not his words!

Structure assignment and its pitfall in c language.

Jan 28 th , 2013 9:47 pm

There is a structure type defined as below:

2 3 4 5

struct __map_t { int code; char name[NAME_SIZE]; char *alias; }map_t;

If we want to assign map_t type variable struct2 to sturct1 , we usually have below 3 ways:

2 3 4 5 6 7 8 9 10

struct1.code = struct2.code; strncpy(struct1.name, struct2.name, NAME_SIZE); struct1.alias = struct2.alias; /* Way #2: memcpy the whole memory content of struct2 to struct1 */ memcpy(&struct1, &struct2, sizeof(struct1)); /* Way #3: straight assignment with '=' */ struct1 = struct2;

Consider above ways, most of programmer won’t use way #1, since it’s so stupid ways compare to other twos, only if we are defining an structure assignment function. So, what’s the difference between way #2 and way #3? And what’s the pitfall of the structure assignment once there is array or pointer member existed? Coming sections maybe helpful for your understanding.

The difference between ‘=’ straight assignment and memcpy

The struct1=struct2; notation is not only more concise , but also shorter and leaves more optimization opportunities to the compiler . The semantic meaning of = is an assignment, while memcpy just copies memory. That’s a huge difference in readability as well, although memcpy does the same in this case.

Copying by straight assignment is probably best, since it’s shorter, easier to read, and has a higher level of abstraction. Instead of saying (to the human reader of the code) “copy these bits from here to there”, and requiring the reader to think about the size argument to the copy, you’re just doing a straight assignment (“copy this value from here to here”). There can be no hesitation about whether or not the size is correct.

Consider that, above source code also has pitfall about the pointer alias, it will lead dangling pointer problem ( It will be introduced below section ). If we use straight structure assignment ‘=’ in C++, we can consider to overload the operator= function , that can dissolve the problem, and the structure assignment usage does not need to do any changes, but structure memcpy does not have such opportunity.

The pitfall of structure assignment:

Beware though, that copying structs that contain pointers to heap-allocated memory can be a bit dangerous, since by doing so you’re aliasing the pointer, and typically making it ambiguous who owns the pointer after the copying operation.

If the structures are of compatible types, yes, you can, with something like:

(dest_struct, source_struct, sizeof(dest_struct));

} The only thing you need to be aware of is that this is a shallow copy. In other words, if you have a char * pointing to a specific string, both structures will point to the same string.

And changing the contents of one of those string fields (the data that the char points to, not the char itself) will change the other as well. For these situations a “deep copy” is really the only choice, and that needs to go in a function. If you want a easy copy without having to manually do each field but with the added bonus of non-shallow string copies, use strdup:

2	(dest_struct, source_struct, sizeof (dest_struct)); dest_struct->strptr = strdup(source_struct->strptr);

This will copy the entire contents of the structure, then deep-copy the string, effectively giving a separate string to each structure. And, if your C implementation doesn’t have a strdup (it’s not part of the ISO standard), you have to allocate new memory for dest_struct pointer member, and copy the data to memory address.

Example of trap:

2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28

#include <stdlib.h> #include <string.h> #define NAME_SIZE 16 typedef struct _map_t { int code; char name[NAME_SIZE]; char *alias; } map_t; int main() { map_t a, b, c; /* initialize the a's members value */ a.code = 1024; snprintf(a.name, NAME_SIZE, "Controller SW3"); char *alias = "RNC&IPA"; a.alias = alias; /* assign the value via memcpy */ memcpy(&b, &a, sizeof(b)); /* assign the value via '=' */ c = a; return 0; }

Below diagram illustrates above source memory layout, if there is a pointer field member, either the straight assignment or memcpy , that will be alias of pointer to point same address. For example, b.alias and c.alias both points to address of a.alias . Once one of them free the pointed address, it will cause another pointer as dangling pointer. It’s dangerous!!

Recommend use straight assignment ‘=’ instead of memcpy.
If structure has pointer or array member, please consider the pointer alias problem, it will lead dangling pointer once incorrect use. Better way is implement structure assignment function in C, and overload the operator= function in C++.
stackoverflow.com: structure assignment or memcpy
stackoverflow.com: assign one struct to another in C
bytes.com: structures assignment
wikipedia: struct in C programming language

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C structs and Pointers

In this article, you will learn-

1.1 C Pointers to struct
1.2 Example: Access members using Pointer
1.3 Dynamic memory allocation of structs
1.4 Example: Dynamic memory allocation of structs

In this tutorial, you’ll learn to use pointers to access to individuals from structs in C programming. You will likewise learn to dynamically allocate memory of struct types.

Before you learn about how pointers can be used with structs, be sure to check these tutorials:

C Pointers to struct

Here’s how you can create pointers to structs.

Here, ptr is a pointer to struct.

Example: Access members using Pointer

To access members of a structure using pointers, we use the -> operator.

In this example, the address of person1 is stored in the personPtr pointer using personPtr = &person1;.

Now, you can access the members of person1 using the personPtr pointer.

By the way,

personPtr->age is equivalent to (*personPtr).age personPtr->weight is equivalent to (*personPtr).weight

Dynamic memory allocation of structs

Before you continue this area, we prescribe you to check C dynamic memory allocation .

Once in awhile, the number of struct variables you declared might be insufficient. You may need to dispense memory during run-time. Here’s the way you can accomplish this in C programming.

Example: Dynamic memory allocation of structs

When you run the program, the output will be:

In the above example, n number of struct factors are made where n is entered by the user.

To designate the memory for n number of struct individual, we used,

Then, we used the ptr pointer to access the elements of the person.

Please feel free to give your comment if you face any difficulty here.

Structure and Union

Written by worldofitech

C Structure and Function

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Structure of c program with example.

Last Updated on July 13, 2023 by Mayank Dham

A structured approach is used in a C program, which includes preprocessor directives, function declarations, global variable declarations, and the main function. Preprocessor directives deal with header files and macros, whereas function declarations define the functions that will be used in the program. The main function serves as the entry point, and global variable declarations define shared variables. Understanding this structure aids in the creation of well-organized and efficient C programs. In this article, we will go over each component with examples to help you write well-structured code.

Basic Structure of C Program

Section	Description
Documentation	Includes the program’s description, the programmer’s name, and the creation date. The majority of these are written as comments.
Link	Includes the program’s description, the programmer’s name, and the creation date. The majority of these are written as comments.
Definition	preprocessor directive that contains symbolic constants is included. For instance, #define enables the usage of constants in our code. In the code, it substitutes its value for each constant.
Global Declaration	Includes the declaration of functions, static global variables, and global variable declarations.
Main() Function	Every C program’s main() function serves as the starting point for execution. A main() function must be present in every C program.
Subprograms	All user-defined methods should be included (functions the user provides). Both built-in functions and function definitions specified in the Global Declaration section may be included there. The main() method is what is used for them.

In order to comprehend the structure of a C program, let’s look at an example:

Example: Write a program to calculate our age.

In the following example, we’ll calculate age concerning a year.

Let’s implement this and check:

You’ve to subtract the current year from your birth year and get your age.

Syntax of Structure in C Program

A structure’s syntax in C is defined by defining a structure name, followed by member variables with their respective data types. Structures enable the grouping of related data under a single name, resulting in a more organized approach to data management. The dot operator can be used to declare and access structure type variables. Utilizing structures in C helps improve code clarity and facilitates efficient handling of data.

Documentation

In a C program, single-line comments can be written using two forward slashes i.e., //, and we can create multi-line comments using / /. Here, we’ve used multi-line comments.

This section includes all header files. A header file is a file that contains C declarations that can be shared among many files. We can use other people’s codes in our files due to it. Before compilation, a copy of these header files is inserted into your code.

Any statement in C that starts with the symbol "#" is referred to be a preprocessor directive. Constants are made using the #define preprocessor compiler command. The usage of constants in our code is fundamentally made possible by #define, which enables the macro declaration.

We’ve established the constant BORN, and we’ve given it the value of 2000. In general, it is better to define the constants using capital characters. Every time the aforementioned constant BORN is used in our code, 2000 will be utilized in its place. In order to make a source program simple to edit and compile in many execution contexts, #define is frequently employed. There is no semicolon at the conclusion of the defined sentence.

Global Declaration

All global variables, function declarations, and static variables are contained in this section. Anywhere in the program can utilize the variables specified in this section. They get access to all of the program’s features. Consequently, they are known as global variables.

Our age function, which accepts a single integer parameter and outputs an integer, has been defined.

Main() Function

This section of a C program’s structure comprises the code’s primary purpose. The main() function is when the compiler begins running code. It may make use of user-defined functions as well as built-in and global variables. The main() function’s return type is not required to be an int and can alternatively be void.

Here, the number 2021 has been assigned to the variable current, which has been defined. After that, we invoked the age() method, which only accepts one parameter, before using the printf() function.

Subprograms

This also applies to the user-defined programs that the main() function calls. Regardless of their sequence, user-defined functions are typically written after the main() function. The program’s control switches to the user-defined function when it is called from the main() function, and it returns to the main() function when it meets a return statement. In this instance, we’ve developed the age() function, which only accepts the current year as an input.

The main function calls this function. The main function receives an integer as a response.

Conclusion The structure of a C program adheres to a strict format to ensure proper organization and execution. Preprocessor directives, function prototypes, the main function, user-defined functions, and variable declarations are all common components of a C program. Following a well-defined structure improves the program’s readability, maintainability, and efficiency. It is critical to follow the structure when writing C programs in order to ensure proper compilation and execution.

Frequently Asked Questions (FAQs):

Q1: What is the basic structure of a C program? A basic structure of a C program typically consists of the following elements: Preprocessor directives Function prototypes The main function User-defined functions

Q2: What are preprocessor directives? Preprocessor directives are lines of code that start with a ‘#’ symbol. They are used to include header files, define macros, or perform conditional compilation. Examples of preprocessor directives include ‘#include’, ‘#define’, and ‘#ifdef’.

Q3: What is the main function in a C program? The main function is the entry point of a C program. It is where the program execution begins. Every C program must have a main function, which returns an integer value to indicate the program’s exit status.

Q4: What are function prototypes? Function prototypes are declarations that specify the name, return type, and parameters of a function before its actual implementation. They provide a forward declaration to the compiler, allowing it to recognize and validate the function calls made within the program.

Q5: Can you provide an example of a C program structure? Certainly! Here’s an example of a simple C program structure:

In this example, the program includes the stdio.h header file using the preprocessor directive #include. It declares a function prototype for the greet function, followed by the main function that prints messages and calls the greet function. Lastly, the greet function is defined to print a greeting message.

What is C Programming Language?

C is a general-purpose, imperative computer programming language, supporting structured programming, lexical variable scope and recursion, while a static type system prevents many unintended operations. C was originally developed by Dennis Ritchie between 1969 and 1973 at Bell Labs. It has since become one of the most widely used programming languages of all time, with C compilers from various vendors available for the majority of existing computer architectures and operating systems.

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Copying structure in C with assignment instead of memcpy() [duplicate]

Up until recently, I have only seen copying of structure fields done with memcpy() . In classes and online instructions, copying the contents of one struct into another generally looks like

However, this task can also be accomplished by a simple assignment replacing the memcpy() .

Is there good reason why this isn't as widely used (at least in my limited experience)? Are these two methods—assignment and memcpy() —equivalent, or is there some compelling reason to use memcpy() in general?

7 In C the two methods are equivalent, and neither of them does a deep copy. – Some programmer dude Commented Nov 8, 2012 at 7:02
4 memcpy(b1, b0, sizeof(struct block)); is very bad style and error-prone. Either use the assignment or memcpy(b1, b0, sizeof *b1); – R.. GitHub STOP HELPING ICE Commented Nov 8, 2012 at 7:04
@R..: you could also probably argue for memcpy(b1, b0, sizeof *b0) . Using sizeof * eliminates one of the two likely errors, using sizeof(struct block) eliminates neither. – Steve Jessop Commented Nov 8, 2012 at 9:26
@Jeyaram forgot to acknowledge you for the edit a while back, thanks. – olliezhu Commented Jun 7, 2013 at 19:35

5 Answers 5

Both methods are equivalent, and perform a shallow copy . This means that the structure itself is copied, but anything the structure references is not copied.

As for why memcpy is more popular, I'm not sure. Older versions of C did not support structure assignment ( although it was a common extension as early as 1978 ), so perhaps the memcpy style stuck as a way of making more portable code? In any case, structure assignment is widely supported in PC compilers, and using memcpy is more error-prone (if you get the size wrong, Bad Things are likely to happen), and so it's best to use structure assignment where possible.

There are, however, cases where only memcpy works. For example:

If you're copying a structure to or from an unaligned buffer - eg, to save/load to/from disk or send/receive on a network - you need to use memcpy , as structure assignment requires both source and destination to be aligned properly.
If you're packing additional information after a structure, perhaps using a zero-element array , you need to use memcpy , and factor this additional information into the size field.
If you're copying an array of structures, it may be more efficient to do a single memcpy rather than looping and copying the structures individually. Then again, it may not. It's hard to say, memcpy implementations differ in their performance characteristics.
Some embedded compilers might not support structure assignment. There's probably other more important things the compiler in question doesn't support as well, of course.

Note also that although in C memcpy and structure assignment are usually equivalent, in C++ memcpy and structure assignment are not equivalent. In general C++ it's best to avoid memcpy ing structures, as structure assignment can, and often is, overloaded to do additional things such as deep copies or reference count management.

Cool, thanks. Sorry about the deep/shallow copy confusion. I was under the impression that a shallow copy was like a pointer assignment, like b1 = b0 instead of *b1 = *b0 . – olliezhu Commented Nov 8, 2012 at 7:09

This could not be the exact answer you looking for.

Im explaining scenario which I met.

when we use memcpy() , it does byte-by-byte copy to destination. so no worry about data alignment in ARM architecture. If you use = operator, and any one of the address is not aligned to 4-byte then alignment fault will come.

From Arm site:

A pointer to the destination location that is one byte beyond the last byte written to. This enables continuation of the writing process with perfect alignment of bytes for string concatenation of memory blocks.

http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.dui0175k/Cihbbjge.html

2 Shouldn't the compiler take care of everything being aligned properly? – alk Commented Nov 8, 2012 at 7:07
2 @alk, the compiler assumes everything is aligned properly, as this allows significant performance improvements on many platforms. If you just use malloc to allocate memory for your structure, it will make sure it's aligned, but if you start doing pointer arithmetic or reading structures from the file or network this is no longer the case and the compiler's assumptions may be violated, causing undefined behavior. Note that you won't see this on x86 as most x86 operations handle unaligned accesses transparently, with a slight performance hit. – bdonlan Commented Nov 8, 2012 at 7:16
@bdonlan Fair enough I see the issues related to reading/writing from/to propably badly aligned I/O-buffers. Anyhow why there should be problems using (properly typed) pointer arithmetics I do not get, as the compiler should know anything needed (at compile time) to generate the correct code. – alk Commented Nov 8, 2012 at 7:42
1 @alk exactly. As long as you play by the rules, everything is aligned. Once you start casting pointers to char * , adding offsets, and casting them back, the compiler no longer knows what's going on. – bdonlan Commented Nov 9, 2012 at 4:56
"The pointer returned if the allocation succeeds is suitably aligned so that it may be assigned to a pointer to any type of object and then used to access such an object or an array of such objects in the space allocated" -- C99 §7.20.3 So alignment is a non issue here and memcpy is no better or worse than structure assignment (except being more error prone). – Craig Barnes Commented Apr 19, 2018 at 15:56

I'm resurrecting this old question because the answers do not explain why memcpy is actually preferred.

memcpy is preferred because it makes it clear the programmer wants to copy the content and not simply the pointers.

In the following example, the two assignments make two very different things:

Inadvertently using one instead of the other may have disastrous effects. The compiler won't complain. Unless the program crashes when an uninitialized pointer is used, the error can go unnoticed for a long time and produce strange side effects.

Writing it as one of:

let the reader knows that the intent is to copy the content (at the expense of type safety and bounds checking).

Some compilers (gcc for instance) even issue a warning about the sizeof when they encounter something like:

In a recent discussion, a colleague maintained that struct assignment was more type safe and thus better. I like your answer, but don't know what to think of my colleague's argument. I suppose both sides have merits. – Thagomizer Commented Jan 13, 2020 at 21:23

Some people prefer memcpy because that's what they learned and they never figured out that they could just do an assignment (in ancient times the assignment wasn't allowed, but that's a long long time ago). There are no alignment problems to worry about since memory allocated by malloc () is always aligned correctly. And since a compiler could trivially translate this assignment to a memcpy call, it would never be slower or more code than memcpy. Of course there are embedded systems with badly outdated compilers.

People working on embedded platform will prefer to use memcopy instead of direct assignment of structure . Mainly when you deal with embedded platform, some compiler doesn't support direct structure assignment, for that you need to use memcopy. if you are working on pc then there is no issue in either case, Both are valid.

Not the answer you're looking for? Browse other questions tagged c pointers struct memcpy or ask your own question .

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Structure of the C Program

The basic structure of a C program is divided into 6 parts which makes it easy to read, modify, document, and understand in a particular format. C program must follow the below-mentioned outline in order to successfully compile and execute. Debugging is easier in a well-structured C program.

Sections of the C Program

There are 6 basic sections responsible for the proper execution of a program. Sections are mentioned below:

Documentation
Preprocessor Section
Global Declaration
Main() Function
Sub Programs

1. Documentation

This section consists of the description of the program, the name of the program, and the creation date and time of the program. It is specified at the start of the program in the form of comments. Documentation can be represented as:

Anything written as comments will be treated as documentation of the program and this will not interfere with the given code. Basically, it gives an overview to the reader of the program.

2. Preprocessor Section

All the header files of the program will be declared in the preprocessor section of the program. Header files help us to access other’s improved code into our code. A copy of these multiple files is inserted into our program before the process of compilation.

3. Definition

Preprocessors are the programs that process our source code before the process of compilation. There are multiple steps which are involved in the writing and execution of the program. Preprocessor directives start with the ‘#’ symbol. The #define preprocessor is used to create a constant throughout the program. Whenever this name is encountered by the compiler, it is replaced by the actual piece of defined code.

4. Global Declaration

The global declaration section contains global variables, function declaration, and static variables. Variables and functions which are declared in this scope can be used anywhere in the program.

5. Main() Function

Every C program must have a main function. The main() function of the program is written in this section. Operations like declaration and execution are performed inside the curly braces of the main program. The return type of the main() function can be int as well as void too. void() main tells the compiler that the program will not return any value. The int main() tells the compiler that the program will return an integer value.

6. Sub Programs

User-defined functions are called in this section of the program. The control of the program is shifted to the called function whenever they are called from the main or outside the main() function. These are specified as per the requirements of the programmer.

Structure of C Program with example

Example: Below C program to find the sum of 2 numbers:

Explanation of the above Program

Below is the explanation of the above program. With a description explaining the program’s meaning and use.

Sections	Description
/** * file: sum.c * author: you * description: program to find sum. */	It is the comment section and is part of the description section of the code.
#include<stdio.h>	Header file which is used for standard input-output. This is the preprocessor section.
#define X 20	This is the definition section. It allows the use of constant X in the code.
int sum(int y)	This is the Global declaration section includes the function declaration that can be used anywhere in the program.
int main()	main() is the first function that is executed in the C program.
{…}	These curly braces mark the beginning and end of the main function.
printf(“Sum: %d”, sum(y));	printf() function is used to print the sum on the screen.
return 0;	We have used int as the return type so we have to return 0 which states that the given program is free from the error and it can be exited successfully.
int sum(int y) { return y + X; }	This is the subprogram section. It includes the user-defined functions that are called in the main() function.

Steps involved in the Compilation and execution of a C program:

Program Creation
Compilation of the program
Execution of the program
The output of the program

Read more about Compiling a C Program Compilation – Behind the Scenes

In this article points we learned about the structure of the C Program are mentioned below: The basic structure of a C program is divided into 6 parts which makes it easy to read, modify, document, and understand in a particular format. Debugging is easier in a well-structured C program. There are 6 sections in a C Program that are Documentation, Preprocessor Section, Definition, Global Declaration, Main() Function, and Sub Programs. There are certain steps while compilation and executing of C program as mentioned below: Creation of Program Compilation of the program Execution of the program Output of the program

FAQs for Structure of C Program

1. what is meant by the structure of a program .

The structure of a program is defined by its control flow, as structures are built up of blocks of codes. These blocks have a single entry and exit in the control flow.

2. What is the structure of C program syntax?

Any C Program can be divided into header, main() function, variable declaration, body, and return type of the program.

3. Why C is a structured program?

C is a structured programming language because it divides the programs into small modules called functions which makes the execution easier.

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How to Debug Memory Allocation Issues in C

Memory management is a fundamental aspect of computer science that plays a critical role in ensuring efficient and effective use of system resources. Understanding how to allocate, deallocate, and reallocate memory is essential for developing robust programs. This guide will help students approach memory management assignments, providing the foundational knowledge and practical steps needed to tackle similar tasks.

In solving programming assignments , particularly those involving C, memory management can often be a challenging area. Proper memory allocation is crucial to prevent issues such as memory leaks and segmentation faults, which can significantly impact the performance and reliability of your programs. Efficient memory management ensures that applications run smoothly and utilize system resources effectively.

When availing C assignment help services, it's important to understand the key components of memory management: allocation, deallocation, and reallocation. Allocation involves reserving a portion of memory for use, deallocation involves releasing the reserved memory when it is no longer needed, and reallocation involves adjusting the size of an allocated memory block.

How to Improve Memory Allocation Efficiency in C

Understanding Memory Management

Memory management involves the allocation, deallocation, and reallocation of memory during the execution of a program. Efficient memory management ensures that applications run smoothly and utilize system resources effectively. The key components of memory management include:

Allocation: Reserving a portion of memory for use.
Deallocation: Releasing the reserved memory when it is no longer needed.
Reallocation: Adjusting the size of an allocated memory block.

Memory Allocation

Memory allocation is the process of reserving a portion of memory during program execution. Various algorithms handle memory allocation, with "First Fit" being a commonly used method. In this algorithm, the allocator searches for the first block of memory that is large enough to satisfy the request.

Steps for Implementation

1. Define a Memory Block Structure: Create a struct to represent each block of memory. This struct should contain information about the block's size, whether it is free or allocated, and pointers to the next and previous blocks in the linked list.

2. Initialize Memory: Set up a function to initialize the memory allocator. This function should create a large block of memory and set up the linked list structure.

3. Allocate Memory: Implement the allocation function that iterates through the linked list to find the first suitable block.

Memory Deallocation

Deallocation is the process of marking a block of memory as free for future use. Handling fragmentation is crucial. Fragmentation occurs when free memory is scattered in small blocks, making it difficult to allocate larger blocks.

1. Free Memory Block: Implement the function to mark a block as free and coalesce adjacent free blocks.

Memory Reallocation

Reallocation adjusts the size of an allocated block. It typically involves allocating a new block of the requested size, copying the old data to the new block, and then freeing the old block.

1. Reallocate Memory Block: Implement the function to resize a block, considering various edge cases.

Additional Tips for Successful Implementation

1. Zero-Fill Allocated Memory: For security and grading purposes, zero-fill the allocated memory before returning a pointer.

2. Handle Edge Cases: Ensure your functions handle cases like zero-size allocation, NULL pointers, and allocation failures gracefully.

3. Testing and Validation: Thoroughly test your allocator with various scenarios, including allocating, freeing, and reallocating memory of different sizes. Check for memory leaks and fragmentation issues.

Best Practices for Memory Management Assignments

Understand the Requirements: Carefully read the assignment prompt and understand what is required. Identify the specific memory management techniques you need to implement.
Plan Your Approach: Before writing code, outline the structure of your memory allocator. Decide how you will implement the linked list, handle allocation, deallocation, and reallocation, and manage edge cases.
Break Down the Problem: Divide the assignment into smaller tasks, such as implementing the memory block structure, creating the initialization function, and writing the allocation, deallocation, and reallocation functions.
Write Clean and Modular Code: Keep your code organized and modular. Use functions to encapsulate different parts of the memory management process. This makes your code easier to read, debug, and maintain.
Test Thoroughly: Create a comprehensive set of test cases to validate your memory allocator. Test various allocation sizes, deallocation scenarios, and reallocation cases. Check for memory leaks and fragmentation.
Document Your Code: Add comments to explain your code. Document the purpose of each function, describe the parameters and return values, and provide an overview of how your memory allocator works.
Seek Feedback: If possible, get feedback from peers or instructors. Review your code and identify areas for improvement. Make necessary adjustments based on the feedback.

Example Assignment Walkthrough

Let's walk through an example assignment related to memory allocation, deallocation, and reallocation. This example will provide a step-by-step guide to help you approach similar assignments.

Assignment: Implement a Memory Allocator

Task: Implement a memory allocator using a linked list of memory blocks. The allocator should handle memory allocation, deallocation, and reallocation.

Requirements:

Allocation function: void *mm_malloc(size_t size)
Deallocation function: void mm_free(void *ptr)
Reallocation function: void *mm_realloc(void *ptr, size_t size)

1. Define the Memory Block Structure: Create a struct to represent each block of memory.

2. Initialize Memory: Implement a function to initialize the memory allocator.

3. Allocate Memory: Implement the allocation function.

4. Deallocate Memory: Implement the deallocation function.

5. Reallocate Memory: Implement the reallocation function.

Testing and Validation

To ensure the correctness of your memory allocator, create a comprehensive set of test cases. These tests should cover various scenarios, including allocating different sizes of memory, freeing memory, and reallocating memory to larger and smaller sizes.

Mastering memory management is essential for developing efficient and reliable programs. By understanding the principles of memory allocation, deallocation, and reallocation, and following a structured approach, you can effectively tackle memory management assignments. This guide provides a comprehensive framework to help you succeed in your memory management tasks, ensuring that you develop robust and efficient solutions. Remember to thoroughly test your allocator and seek feedback to continually improve your skills.

1 H, 13 C and 15 N resonance assignments of a shark variable new antigen receptor against hyaluronan synthase

Published: 14 August 2024

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Yuxin Liu 1 , 2 , 3 ,
Hao Wang 2 , 3 ,
Cookson K. C. Chiu 4 ,
Yujie Wu 4 &
Yunchen Bi 2 , 3

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Single domain antibody (sdAb) is only composed of a variable domain of the heavy-chain-only antibody, which is devoid of light chain and naturally occurring in camelids and cartilaginous fishes. Variable New Antigen Receptor (VNAR), a type of single domain antibody present in cartilaginous fishes such as sharks, is the smallest functional antigen-binding fragment found in nature. The unique features, including flexible paratope, high solubility and outstanding stability make VNAR a promising prospect in antibody drug development and structural biology research. However, VNAR’s research has lagged behind camelid-derived sdAb, especially in the field of structural research. Here we report the 1 H, 15 N, 13 C resonance assignments of a VNAR derived from the immune library of Chiloscyllium plagiosum , termed B2-3, which recognizes the hyaluronan synthase. Analysis of the backbone chemical shifts demonstrates that the secondary structure of VNAR is predominately composed of β-sheets corresponding to around 40% of the B2-3 backbone. The Cβ chemical shift values of cysteine residues, combined with mass spectrometry data, clearly shows that B2-3 contains two pairs of disulfide bonds, which is import for protein stability. The assignments will be essential for determining the high resolution solution structure of B2-3 by NMR spectroscopy.

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Selection and Characterization of Anti-idiotypic Shark Antibody Domains

In vitro maturation of a humanized shark vnar domain to improve its biophysical properties.

A synthetic library for rapid isolation of humanized single-domain antibodies

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The assigned 1 H, 15 N and 13 C chemical shift of B2-3 VNAR has been deposited in the BioMagResBank ( http://www.bmrb.wisc.edu/ ) under the accession number 52,417.

Berjanskii MV, Wishart DS (2005) A simple method to predict protein flexibility using secondary Chemical shifts. J Am Chem Soc 127(43):14970–14971. https://doi.org/10.1021/ja054842f

Article Google Scholar

Delaglio F, Grzesiek S, Vuister GW, Zhu G, Pfeifer J, Bax A (1995) NMRPipe: a multidimensional spectral processing system based on UNIX pipes. J Biomol NMR 6(3):277–293. https://doi.org/10.1007/BF00197809

Diaz M, Greenberg AS, Flajnik MF (1998) Somatic hypermutation of the new antigen receptor gene (NAR) in the nurse shark does not generate the repertoire: possible role in antigen-driven reactions in the absence of germinal centers. Proc Natl Acad Sci U S A 95(24):14343–14348. https://doi.org/10.1073/pnas.95.24.14343

Article ADS Google Scholar

Greenberg AS, Avila D, Hughes M, Hughes A, McKinney EC, Flajnik MF (1995) A new antigen receptor gene family that undergoes rearrangement and extensive somatic diversification in sharks. Nature 374(6518):168–173. https://doi.org/10.1038/374168a0

Hamers-Casterman C, Atarhouch T, Muyldermans S, Robinson G, Hamers C, Songa EB, Bendahman N, Hamers R (1993) Naturally occurring antibodies devoid of light chains. Nature 363(6428):446–448. https://doi.org/10.1038/363446a0

Liu W, Song H, Chen Q, Yu J, Xian M, Nian R, Feng D (2018) Recent advances in the selection and identification of antigen-specific nanobodies. Mol Immunol 96:37–47. https://doi.org/10.1016/j.molimm.2018.02.012

Markley JL, Bax A, Arata Y, Hilbers CW, Kaptein R, Sykes BD, Wright PE, Wuthrich K (1998) Recommendations for the presentation of NMR structures of proteins and nucleic acids. IUPAC-IUBMB-IUPAB Inter-union Task Group on the Standardization of Data Bases of Protein and nucleic acid structures determined by NMR spectroscopy. J Biomol NMR 12(1):1–23. https://doi.org/10.1023/a:1008290618449

Muyldermans S (2013) Nanobodies: natural single-domain antibodies. Annu Rev Biochem 82:775–797. https://doi.org/10.1146/annurev-biochem-063011-092449

Muyldermans S (2021) Applications of Nanobodies. Annu Rev Anim Biosci 9:401–421. https://doi.org/10.1146/annurev-animal-021419-083831

Pardon E, Laeremans T, Triest S, Rasmussen SG, Wohlkonig A, Ruf A, Muyldermans S, Hol WG, Kobilka BK, Steyaert J (2014) A general protocol for the generation of Nanobodies for structural biology. Nat Protoc 9(3):674–693. https://doi.org/10.1038/nprot.2014.039

Shen Y, Bax A (2013) Protein backbone and sidechain torsion angles predicted from NMR chemical shifts using artificial neural networks. J Biomol NMR 56(3):227–241. https://doi.org/10.1007/s10858-013-9741-y

Ubah OC, Lake EW, Gunaratne GS, Gallant JP, Fernie M, Robertson AJ, Marchant JS, Bold TD, Langlois RA, Matchett WE, Thiede JM, Shi K, Yin L, Moeller NH, Banerjee S, Ferguson L, Kovaleva M, Porter AJ, Aihara H, LeBeau AM, Barelle CJ (2021) Mechanisms of SARS-CoV-2 neutralization by shark variable new antigen receptors elucidated through X-ray crystallography. Nat Commun 12(1):7325. https://doi.org/10.1038/s41467-021-27611-y

Wei L, Wang M, Xiang H, Jiang Y, Gong J, Su D, Al Azad MAR, Dong H, Feng L, Wu J, Chan LL, Yang N, Shi J (2021) Bamboo shark as a small animal model for single domain antibody production. Front Bioeng Biotechnol 9:792111. https://doi.org/10.3389/fbioe.2021.792111

Zielonka S, Empting M, Grzeschik J, Konning D, Barelle CJ, Kolmar H (2015) Structural insights and biomedical potential of IgNAR scaffolds from sharks. MAbs 7(1):15–25. https://doi.org/10.4161/19420862.2015.989032

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Acknowledgements

We thank for grant supports from the National Natural Science Foundation of China (Grant Number: 42376136), Research on Simulation Technology and Device of Key Processes of Typical Marine Ecological Disasters in the Pre-Research Project of Major Scientific Facilities in Shandong Province (DKXZZ202205). We thank the staffs at the Intelligent Simulator of Marine Ecosystems, ISME and the staffs at the mass spectrometry system at the Shenzhen Bay Laboratory for instrument support and technical assistance. This work is also supported by Oceanographic Data Center, IOCAS.

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CAS and Shandong Province Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, China

Yuxin Liu, Hao Wang & Yunchen Bi

Laboratory for Marine Biology and Biotechnology, Qingdao Marine Science and Technology Center, Qingdao, China

Shenzhen Bay Laboratory, Shenzhen, China

Cookson K. C. Chiu & Yujie Wu

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Y.L. , C.C. and Y.W. performed the experiments. H.W. and Y.B. wrote the main manuscript text and H.W. prepared figures. All authors reviewed the manuscript.

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Liu, Y., Wang, H., Chiu, C.K.C. et al. 1 H, 13 C and 15 N resonance assignments of a shark variable new antigen receptor against hyaluronan synthase. Biomol NMR Assign (2024). https://doi.org/10.1007/s12104-024-10190-6

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