function declaration in c code example

Example 1: what is system function in c

The system() function is a part of the C/C++ standard library. It is used to pass the commands that can be executed in the command processor or the terminal of the operating system, and finally returns the command after it has been completed.

<stdlib.h> or <cstdlib> should be included to call this function

Example 2: function in c

#include <stdio.h>

void function(){
  printf("I am a function!");
}

int main(void) {
  
  function();
}

Example 3: how to write function in c

#include <stdio.h>

// Here is a function declaraction
// It is declared as "int", meaning it returns an integer
/*
	Here are the return types you can use:
    	char,
        double,
        float,
        int,
        void(meaning there is no return type)
*/
int MyAge() {
	return 25;
}

// MAIN FUNCTION
int main(void) {
	// CALLING THE FUNCTION WE MADE
    MyAge();
}

Example 4: functions in c programming

#include <stdio.h>
/* function return type is void and it doesn't have parameters*/
void introduction()
{
    printf("Hi\n");
    printf("My name is Chaitanya\n");
    printf("How are you?");
    /* There is no return statement inside this function, since its
     * return type is void
     */
}

int main()
{
     /*calling function*/
     introduction();
     return 0;
}

Example 5: functions in c programming

#include <stdio.h>
int addition(int num1, int num2)
{
     int sum;
     /* Arguments are used here*/
     sum = num1+num2;

     /* Function return type is integer so we are returning
      * an integer value, the sum of the passed numbers.
      */
     return sum;
}

int main()
{
     int var1, var2;
     printf("Enter number 1: ");
     scanf("%d",&var1);
     printf("Enter number 2: ");
     scanf("%d",&var2);

     /* Calling the function here, the function return type
      * is integer so we need an integer variable to hold the
      * returned value of this function.
      */
     int res = addition(var1, var2);
     printf ("Output: %d", res);

     return 0;
}