Introduction of Function in c programming | function in c

 Function in c 

What is function in c programming?

A function is a piece of code which performs a particular task given by the programmer.

                              or

C Function is a group of statements. There is a function in every program. for e.g. The main () function is also written in the program. Function calls are made where the function is required.

Why we use function in c programming?

There are so many reasons to use the function in c programming which is mentioned below:

Sometimes our program gets bigger in size and it is not possible for a programmer to track which piece of code is doing what.

The function is a way to break our code into chunks so that it is possible for a programmer to reuse them.

The code written in the function does not have to be written again and again.

The function Programmer saves time and space for the program.

Larger programs can be divided into smaller functions.

If a said error in the program, then it can be easily removed.

The function can be called again and again where needed.

How we can write any function in c programming

Function has a specific name. At the beginning of the function, its name is followed by two parenthesis () and function statements are two curly braces {}

Syntax of a function

#include <stdio.h> Void add();                    = Function prototype   Int main() { Int a; void add();                            = Function call Getch(); }   Void add() { Printf(“you can add two or maore then two numbers ”)                                                = Function definition  }

 
What is Function prototype?

Function prototype is a way to tell the compiler about the function we are going to define in the program. Here void indicates that the function returns nothing

Function call

A function call is a way to tell the compiler to execute the function body at the time the call is made

Note that the program execution starts from the main function in the sequence, the instructions are written

Function definition

This part contains the exact set of instructions which are executed during the function call. When a function is called from main (), the main function falls asleep and gets temporarily suspended. During this time the control goes to the function being called. When the function body is done executing main () resumes.

I hope, you understand what is prototype function, function call and function definition

Types of function.

There are two types of functions.

• In-built / Predefined Function

• User-defined Function

 
What is In-built / Predefined Function?

• In-built Functions are also called predefined or Library Functions.

• In-built Functions, separate header file or preprocessor is created for each of the functions.

• The declaration of a function occurs in the definition header files.

• C has a lot of header files and has different functions grouped in them.

• If the programmer wishes, he can also create his own header files.

For example

printf (): This function stdio.h comes under this header file. If the programmer #include <stdio.h> does not include it in the preprocessor program, then printf cannot be used.

strlen (): This function string.h comes under this header file. If the programmer #include <string.h> does not include it in the preprocessor program, then strlen cannot be used.

 What is User-defined Function?

A user-defined function has three divisions.

• Function Declaration

• Function calling

• Function Definition

 

In Function Declaration

While creating a function, the compiler has to tell what kind of function you want to create, this process is called Function Declaration.

 

Syntax for Function Declaration

return_type function_name (parameter (s));

 

Function Declaration has four departments.

• return_type

• function_name

• parameter (s) / argument (s)

• semicolon

 

What is return_type?

 

Each function returns a value, be it null (void) or numeric (int, float, double) or character (char). The return_type of the function is void default. The return_type of the function is in the requirement of the program.

 

What is function_name?

 

The name of the function should be according to its code. Even if there is no, the compiler runs, but it is not called Good Programming. Function name does not have any keyword of C. There are also parameters inside the parenthesis () of the function of C. The function name is case-sensitive. for eg. hello () and hello () are both different functions.

 

What is parameter (s) / argument (s)?

 

Function arguments are data_types or names of their variables with the data type. What type of value a user wants to receive through function calling, it is declared in the argument of the function.

 

What is a semicolon?

After the Declaration of every function, a semicolon is given. This is also part of the function declaration.

 

Example

Function Declaration with two parameters

int add (int a, int b); // function declaration

 

Function Declaration without parameter (s)

int add ();

 

Function Declaration with one parameter

int add (int a);

 

What is Function Calling?

Function calling only has the function name, arguments, and semicolon of the function. Below given example function's return type is 'integer'. The name of the function is 'add' and the function is passed with two parameters meaning a and b. The declaration and definition of the function is of no importance until the function is called.

The syntax for Function Calling

function name (Parameter1, Parameter2. Parameter n);

Example

Function calling with two parameters

add (a, b); // function calling

 

Function calling without parameter (s)

add ();

 

Function calling with one parameter

add (a);

Function Definition

The syntax for Function Definition

return_type function_name (Parameter (s)) {      function_body;   }

 

 

There are four parts to a function definition.

1. return_type

Each function returns a value, be it null (void) or numeric (int, float, double) or character (char). The return_type of the function is void default. The return_type of the function is in the requirement of the program.

 

2. function_name

The name of the function should be according to its code. Even if there is no, the compiler runs, but it is not called Good Programming. The function name does not have any keyword of C. There are also parameters inside the parenthesis () of the function of C. The function name is case-sensitive. for eg. hello () and hello () are both different functions.

 

3. parameter (s) / argument (s)

Function arguments are data_types or names of their variables with the data type. What type of value a user wants to receive through function calling, it is declared in the argument of the function.

 

4. function_body

Function body has variables, but due to being inside the function, their scope is Local. There are some statement (s) inside the body and value returns.

 

Example for Function Definition

int add (int x, int y)  { // function definition int z; z = x + y;   return z; }

 

 

Full Example for Function

#include <stdio.h>   int add (int a, int b); // function declaration with argument   int main () {   int a, b, c; printf ("Enter value of a and b:"); scanf ("% d% d", & a, & b);   c = add (a, b); // funtion calling   printf ("Addition of a and b:% d", c);   return 0; }   int add (int x, int y) {// function definition   int z; z = x + y;   return z; }

 

 

Before learning Call By Value and Call By Reference, understand Parameters.

There are two types of parameters in a function.

 

• Formal parameter

• Actual parameter

 

Formal parameter

The parameters that are written in the declaration of the function and in the definition are called Formal Parameters.

 

For example

void swap (int x, int y); // Formal Parameters int main () { int a = 2; b = 10 swap (a, b) } void swap (int x, int y) {// Formal Parameters ------------ ------------ }

 
Actual parameter

The parameters that are written in a function call are called Actual Parameter.

For example:

 

void swap (int x, int y); int main () { int a = 2; b = 10 swap (a, b) // Actual Parameter } void swap (int x, int y) { ------------ ------------ }

 

There are two types of Function Calling.

• Call by value

• Call by reference

 

1. Call By Value

In Call By Value, the value of Variable is passed to the function as a parameter.

In the Call By Value, the value of the actual parameter is copied to the Formal Parameter.

 

Here variable 'a' and 'b' function 'add' have been passed in the program.

 

Here 'a' and 'b' are copied to the values ​​'x' and 'y' variable.

For example:

 

#include <stdio.h>   void swap (int x, int y);   int main () {   int a = 2, b = 10; printf ("Before Swapping a =% d and b =% d \ n", a, b); swap (a, b); } void swap (int x, int y) { int temp; temp = x; x = y; y = temp; printf ("After Swapping a =% d and b =% d", x, y); }

 

 

2. Call By Reference

In Call By Reference, the address of Variable is passed to the function as a parameter.

In Call By Value, the value of the actual parameter is not copied to the Formal Parameter.

 

Here the variable 'a' and 'b' address are passed to function 'add' in the program.

 

Here 'a' and 'b' are not copied to the values ​​'x' and 'y' variable.

 

It only holds the address hold of the variables.

 

For example

#include <stdio.h>   void swap (int * x, int * y);   int main () {   int a = 2, b = 10; printf ("Before Swapping a =% d and b =% d \ n", a, b); swap (& a, & b); } void swap (int * x, int * y) { int temp; temp = * x; * x = * y; * y = temp; printf ("After Swapping a =% d and b =% d", * x, * y); }

In this article, we looked at the introduction of function. Now we will see its best examples in the next article. Please, the next article is going to be very important, so I will definitely name it Function Part 2.

please read my next article

Thanks for reading this article

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