Unreferenced Libraries?

JediSpam

Alright,

I am having a lot of trouble correctly linking libraries to QT 4. I created a simple library called test_class and here is the code:

test_class.cpp
@
#include "test_class.h"

int test_me::whatever(void)
{
return 5;
}
@

test_class.h
@
#ifndef TEST_CLASS_H
#define TEST_CLASS_H

class test_me
{
public:
int whatever(void);
};

#endif
@

I then create that into a .lib and try to call it from my other program in this manner:
@
MainWindow.cpp

test_me abc;
abc.whatever();

@

I have the proper include in MainWindow.cpp and I have the library in my .pro file correct. Any ideas? I'm getting this as an error:

Quoted

mainwindow.cpp:26: error: undefined reference to `test_me::whatever()'
:-1: error: collect2: ld returned 1 exit status

lgeyer

Have you added the library to LIBS? Is it properly listed in the linker command when compiling / linking the project?
@
LIBS += -L<path to library> -l<library name>
@

JediSpam

Yes i have added the library to my .pro file
@
unix|win32: LIBS += -ltest_code -LC:\VS13_VIEWS\libs
@

just tried the syntax you posted and still no go

loladiro

You are not exporting the class.
If you are using Qt Creator, have a look at the library template.

lgeyer

[quote author="JediSpam" date="1313071868"]I then create that into a .lib[/quote]

Are we talking about a static library or a shared library?

JediSpam

[quote author="Lukas Geyer" date="1313072764"][quote author="JediSpam" date="1313071868"]I then create that into a .lib[/quote]

Are we talking about a static library or a shared library? If so you will have to export symbols as loladiro said.[/quote]

this is a static library i have created in visual studio 2003. i'm trying to understand the library template stuff

lgeyer

You might use the nm tool to see which symbols are exported from your library.

loladiro

[quote]
this is a static library i have created in visual studio 2003.
[/quote]
Are you trying to mix MSVC and MinGW-compiled code? Not a good Idea!!

printingesco

You talking about static library ?

JediSpam

[quote author="printingesco" date="1313075382"]You talking about static library ?[/quote]

yes

JediSpam

[quote author="loladiro" date="1313072534"]You are not exporting the class.
If you are using Qt Creator, have a look at the library template.[/quote]

I read the qMake Project Files section "Declaring Other Libraries" and don't see what I haven't done correctly.

[quote author="Lukas Geyer" date="1313072949"]You might use the nm tool to see which symbols are exported from your library.[/quote]

Is this a QT tool I don't see it anywhere

loladiro

Again, did you compile your library with mingw? It doesn't seem that way because mingw static library files have a .a extension. You cannot mix MSVC and MinGW.

JediSpam

[quote author="loladiro" date="1313076573"]Again, did you compile your library with mingw? It doesn't seem that way because mingw static library files have a .a extension. You cannot mix MSVC and MinGW.[/quote]

ah i see. so i'd have to use the MinGW in visual studio to build a library.

loladiro

You'd have to either build both the library and app with MinGW or both with MSVC.

lgeyer

[quote author="JediSpam" date="1313076335"]
[quote author="Lukas Geyer" date="1313072949"]You might use the nm tool to see which symbols are exported from your library.[/quote]
Is this a QT tool I don't see it anywhere
[/quote]

nm comes with MinGW, which is part of the Qt SDK. Just open a Qt command promt and type nm <binary> to get a list of exported symbols.

(Although it comes with MinGW it should work with any PE - read MSVC - binaries).

JediSpam

Thanks for the help guys!