try yourself |run program

#include <stdio.h> 
#include <conio.h> 

int s;
int returnVal(int a, int b){
  s = a + b;
 return s;
}

void main(){ 
 int res;
 clrscr();
 printf("\n This is parameterize function program."); 
 res = returnVal(10, 20);
 printf("\n result = %d",res);
 getch();
}

Program Output

This is parameterize function program.
result = 30