包含头文件时出现问题

Question

So i'm having a problem when i try to include a header file. I am defining a header and including it in all of my files but i'm getting this error "unresolved external symbol "void_cdecl print(void)"(?print@@YAXXZ) referenced in function main.

my main file TEST.cpp

#include "stdafx.h"
#include "Header1.h"
using namespace std;
int main()
{
    print();
    return 0;
}

i've only made a simple print function which i define here in Source1.cpp

#include "Header1.h"

void print() {
    cout << "HELLO WORLD" << endl;
}

and my header file looks like this - Header1.h

#pragma once
#ifndef HEADER1_H
#define HEADER1_H

void print();
#endif

I did some research i found that this problem is often caused by spelling mistakes but i really cant see it.

Answer 1

i've only made a simple print function which i define here in Source1.cpp

this file name should be Header1.cpp

 #include "Header1.h"

 void print() {
    cout << "HELLO WORLD" << endl;
 }

Answer 2

You have a linkage problem.

You've to compile Source1.cpp and to link it.

Answer 3

You are missing std::iostream:

 #include "Header1.h"
 #include <iostream>
 using namespace std;

 void print() {
    cout << "HELLO WORLD" << endl;
 }