C++ learning header files. What's up with this semicolon? [closed]

Question

I'm learning to make header files. Here's my code (three separate files)

//Main.cpp
#include <iostream>
#include "functions.h"
;
using namespace std;

int main()
{
    cout << multiply(3, 4) << endl;

    return 0;
}

//functions.cpp
int multiply(int x, int y)
{
    return x * y;
}

//functions.h
#ifndef FUNCTIONS_H_
#define FUNCTIONS_H_

int multiply(int x, int y)

#endif

The code compiles and runs, but the part that's bothering me is in Main.cpp. There's that semicolon under "functions.h" and above "using namespace."

I put it there because visual studio said it was expecting one, but I have no idea why. I don't see it in tutorials.

Sure, it works. But I don't like not knowing why it's there and that it shouldn't be.

Answer 1

Because you miss one semicolon in functions.h

int multiply(int x, int y);
                          ^^^^ here

C++ separates statements with a semicolon.

The #include directive causes the contents of the "functions.h" file to be sent along with the contents of your file to the compiler. The result of this is that compilation errors caused by mistakes in header files are often reported in the code which includes them.(thx to Philipp)

Answer 2

Since the C preprocessor knows nothing about the syntax of C at all - you can use it to put together emails, assembler source files or HTML if you like, it just puts all the source in one long file for the compiler to actually compile.

And you are missing a semicolon after int multiply(int x, int y) in "functions.h".