Trying a function, but I keep getting an error

Question

The goal is for the function to say hi ("Hello User"), but it keeps telling me that my sayHi function is invalid. I'm not sure why.

#include <stdio.h>
#include <stdlib.h>

int main(){
    
    sayHi();
    return 0;
}


void sayHi () 
{
    
  printf ("Hello User");

}

Answer 1

You need to either forward declare the function, or put the definition before main(), so that the compiler knows about the function being called.

Answer 2

You can either try this

#include <stdio.h>
#include <stdlib.h>

void sayHi();

int main() {
  sayHi();
  return 0;
}


void sayHi() {
  printf ("Hello User");

}

or this

#include <stdio.h>
#include <stdlib.h>

void sayHi() {
  printf ("Hello User");

}

int main() {
  sayHi();
  return 0;
}