Linking files

How do you link files in MSVC++6? (i.e. I want to keep certain class declarations separate from main() for size management purposes) and do i have to declare objects, functions and variables extern if they are defined in a separate file? if so, how?
thanks in advance

Quote:

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and do i have to declare objects, functions and variables extern if they are defined in a separate file? if so, how?

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I wondered this same thing a little while back.

Here's how it works (just a dumb example):

SomeHeader.H

Code:

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void myFunction()
{
cout << "\nHello World!";
}

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MySourceFile.CPP

Code:

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#include <iostream.h>
#include "SomeHeader.h"

void myFunction();

int main()
{
myFunction;
return 0;
}

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See the bold-italic text in the source code? It wont work without that. Even though the function is already defined in a header file which is included in the build, your program wont know what myFunction() is, or what it does. So, you must put a function prototype in there before you call it, so that your program knows what to expect when it calls the function (Hmm... was that a good way to word it?)


Variables and other things work similarly.

If you initialize a variable in a header file, you must write it's type into any other files that it'll be used in:

Header1.H

Code:

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int x = 5;

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Then, (for example) if you want to print out x's value in some other header file, you'd do the following:

Header2.H

Code:

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int x ;
cout << x;

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Once again, you must include the int x; line in Header2.H, or else when you try to display x, your program wont know what/where to look for.

Hope that helps;)