Trying a function, but I keep getting an error-CodePudding

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");

}

CodePudding user response：

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;
}

CodePudding user response：

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