Dynamic library in windows

[themean]

Hi
I want to make dynamic library on windows
I using qt creator 2.4 and msvc 2010

In qmake i write this commands

QT -= core gui
 
TEMPLATE = lib
 
CONFIG  += dll

QT -= core gui

TEMPLATE = lib

CONFIG  += dll

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Project build without issues but in in build directory i found only .dll file without .lib file
( I need from this .lib to link to this .dll )
What im doing wrong ???

[ChrisW67]

Does your code export any symbols? It's possible that there will be no import library if there are no exported symbols to import. See Creating Shared Libraries. I get an import library when I do a trivial example using the MingW tools (I don't have MSVC handy) but GCC exports by default.

Does this simple example do what you expect?

// Pro file
TEMPLATE = lib
QT -= core gui
CONFIG += dll
DEFINES += MYSHAREDLIB_LIBRARY
SOURCES += mysharedlib.cpp
 
// mysharedlib.h
 
#include <QtCore/QtGlobal>
#if defined(MYSHAREDLIB_LIBRARY)
#  define MYSHAREDLIB_EXPORT Q_DECL_EXPORT
#else
#  define MYSHAREDLIB_EXPORT Q_DECL_IMPORT
#endif
 
MYSHAREDLIB_EXPORT int doSomethingInsightful();
 
class MYSHAREDLIB_EXPORT ExportedClass {
    ExportedClass();
    int doSomething();
};
 
// mysharedlib.cpp
 
#include "mysharedlib.h"
 
int doSomethingInsightful()
{
    return 42;
}
 
ExportedClass::ExportedClass() 
{
}
 
int ExportedClass::doSomething()
{ 
    return 0;
}

// Pro file
TEMPLATE = lib
QT -= core gui
CONFIG += dll
DEFINES += MYSHAREDLIB_LIBRARY
SOURCES += mysharedlib.cpp

// mysharedlib.h

#include <QtCore/QtGlobal>
#if defined(MYSHAREDLIB_LIBRARY)
#  define MYSHAREDLIB_EXPORT Q_DECL_EXPORT
#else
#  define MYSHAREDLIB_EXPORT Q_DECL_IMPORT
#endif

MYSHAREDLIB_EXPORT int doSomethingInsightful();

class MYSHAREDLIB_EXPORT ExportedClass {
    ExportedClass();
    int doSomething();
};

// mysharedlib.cpp

#include "mysharedlib.h"

int doSomethingInsightful()
{
    return 42;
}

ExportedClass::ExportedClass() 
{
}

int ExportedClass::doSomething()
{ 
    return 0;
}

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[themean]

Thanks
Is it possible for some one that not use Qt ,Qt creator or qmake to use
this library build in that way

[ChrisW67]

Yes, as long as the DLL does not link to any Qt component. The above uses macros defined by Qt headers but you could easily produce a non-Qt version of those macros to provide complete independence.

With the C++ example the user would have to be using the same compiler/linker type to cope with name mangling: e.g. if you built the DLL with MSVC they would need to use MSVC, if you build with MinGW/GCC they would need to use GCC.

If the interface is C-style then any compiler/linker should be able to use it.