Function Passing No Arguments and Returning no Value

Write a program to functions to passing no arguments an returning no values.

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

void sum (void);

void main()
{

  sum();

  getch();
}
void sum(void){
  int add, a, b;
  
  printf("Enter two numbers:");
  scanf("%d%d",&a,&b);
  
  add=a+b;
  
  printf("n the sum is %d",add);
}

Output