Comments on: 1.8 — Programs with multiple files

By: bjb126

bjb126 — Thu, 29 Jul 2010 23:02:19 +0000

I tried compiling my main.cpp in Miscrosoft Visual Studio 2010 and I got this error.

1>Test2.obj : error LNK2005: _main already defined in main.obj
1>c:usersherminedocumentsvisual studio 2010ProjectsTest2DebugTest2.exe : fatal error LNK1169: one or more multiply defined symbols found

By: Kraig

Kraig — Fri, 23 Jul 2010 02:09:04 +0000

For Visual Studio users you need to have the code in add.cpp as follows

#include “stdafx.h”

#include

int add(int x, int y)
{
return x + y;
}

By: villain222

villain222 — Sat, 10 Jul 2010 04:31:17 +0000

ok. i found my problem with code::blocks. whatever your second file is, you just have to goto the left tree window and right click your file (not the main) pick properties goto build tab and make sure compile and Link boxes are checked as well as the debug and release. once i did that I had no problems. why it wasn’t already set? not sure.

By: Mariusz

Mariusz — Wed, 07 Jul 2010 12:07:30 +0000

Wait, is Code::Blocks an IDE, a kind of equivalent to Visual C++…? Then my problem is solved hehe.

By: Mariusz

Mariusz — Wed, 07 Jul 2010 10:43:57 +0000

Hi,
I have a problem with Code::Blocks. I’ve successfully followed all instructions in this chapter up to a point : “In Code::Blocks, go to the file menu and choose “new file”…” and so on. I have no clue on what to do at this point. I’m using Visual C++ 2005 Express and can’t even locate Code::Blocks. I’m completely lost at this point.
Please, anyone help me.

By: Chip

Chip — Sun, 23 May 2010 15:03:56 +0000

Hi.

I was trying to declare some struct types and enum types along with a few variables (of those types)in a separate file. In the header file I’ve just included declaration of the variables with the extern keyword. (Yes, I’m using global variables, but I’m new to C++ and i couldn’t figure out any other way. Besides it’s not that big of a program to be that difficult to track down the variables.) But when the compiler gets to

#include “buildings.h” //the header file

it gives an error because it doesn’t recognize the structs I’ve declared in the separate file as types. If I declare the types in the main file before the line

#include “buildings.h”

it’s all OK, but my idea was to keep the whole program somewhat clean so the types declarations and the variables of that types to be in the same separate file.

Is there something I could do to make the whole project easier to understand by keeping the variables and their custom made types (structs, enums)in one file and each function in a separate file, without having to crowd the main file code with type declarations?

P.S. Great lessons. Very comprehensible.

By: ziyad

ziyad — Mon, 17 May 2010 08:07:36 +0000

file register system

By: Bram Verspeek

Bram Verspeek — Tue, 11 May 2010 20:35:37 +0000

after int add(int x,inty) should be a ;
after int main() there shouldn’t be a ;
I think the stdafx.h should be between

instead of ” “

By: Bram Verspeek

Bram Verspeek — Tue, 11 May 2010 16:19:22 +0000

I have a question related to the multiple files programs.
Is it possible to define a value in the main program and use it in a function without supplying it as an argument?

Say in main.cpp I have

int a = 4

and then in math.cpp I have

//included so the program knows a should be an integer value
int a;

//function definitions
int add(int x,int y)
{
	cout << "a = " << a <
if i run code with this it prints a = 0 instead of a = 4. Is it possible to do this? basically declare global  variables that apply in every party of the program? I read a bit on so would a #define do what I want?

By: armian

armian — Sat, 08 May 2010 20:52:46 +0000

do i need to use include ‘’stdafx.h”?