Arguments are passed to parameters automatically if no argument is provided
in the function call.

Default

Explanation:

When a Function is called, you pass a value to the parameter in function Call, and control is transferred to function definition. Parameters are optional that is, a function may contain no parameters.

Function definition contains the block of code to perform a specific task. Default arguments are passed to parameters in function definition if no argument is passed in function call.

Example: C program

#include <stdio.h>    

int s();  //Function declaration

 int main()  

{  

   int n;  

   n = s();  //Function calling with no parameters

   printf("\nSum  = %d", n);  

   return 0;  

}    

int s()  //Function definition

{  

   int c = 50, d = 80, s;  

   s = (c) + (d);  

   return s;  

}

Output:

Sum=130