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Functions in C

Functions in C programming are defined as simply a set of statements which are executed one by one. Every program in C contains various functions which perform a particular task defined.

Assume Functions in C language like,

Inside IT Companies there are different persons performing different functions like managers Function is different, Employees Function is different. Each Person performs his own task. Similarly, In Programming Language Functions are different blocks of statements which performs their own tasks.

Syntax

returnType functionName()
{
  statement 1;
  statement 2; 
}

returnType indicates the type that function returns. Type may be Integer , Float ,Double , void etc.

functionName() indicates the name of user-defined function.

statement 1; statement 2 indicates the statements you want to execute.

void main()
{
  displayMessage ();
  printf("Hey ! This is my first function :-: ");
}

displayMessage()
{
 printf("Yeppiee ! Main Method Called me :-: ");
}

Output:-

Yeppiee ! Main Method Called me :-: 
Hey ! This is my first function :-:

This was the very basic example for understanding what actually function does .

Main() Function

This is the entry point of any C Program. This is where the program starts. Yeah, of course, you may write every 10's of thousands of lines inside the main. But think Is it readable later in future ? So why not to break those 1000 lines statements into Functions and let that function handle the statements. That's why Functions are introduced into C Language.

Program showing how to perform function declaration

#include <stdio.h>
int main( )
{
    /* This is how you declare a function */
    float square (float) ;
    
    float a, b ;
    printf ("\nEnter any number ") ;
    scanf ("%f", &a) ;
    
    b = square (a) ;
    printf ("\nSquare of %f is %f", a, b) ;
    return 0;
}

/* Function Square with float returnType */
float square (float x)
{
    float y ;
    y = x * x;
    return (y) ;
}

Output

Enter any number 1.5
Square of 1.5 is 2.250000 

Enter any number 2.5 
Square of 2.5 is 6.250000

Function Definition in C Programming

Function defination provides the actual body of the function. The statements we had written inside square function is called as providing the body to any function.So for square function , Function Defination will look like this

float square ( float x )
{
float y ;
y = x * x;
return (y) ;
}

Solve the Quiz of Article

1) What do you think every function returns a value?
Yes
No

2) What do you think the output of following program will be Hi Hello or not?
#include<stdio.h>
int i;
int display();

int main()
{
    while(i)
    {
        display();
        main();
    }
    printf("Codzify\n");
    return 0;
}
int display()
{
    printf("Hi");
}
Yes
No


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