Development/Tutorials/First program

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Revision as of 18:01, 3 January 2007 by Milliams (talk | contribs) (Fit in better with the tutorial series)
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Your first program shall greet the world with a friendly "hello world", what else ? For that, we will use a KMessageBox. To get more information about the KMessageBox-Class, type "kde: kmessagebox" in your konqueror and it will redirect you to

  1. include <QString>
  2. include <kapplication.h>
  3. include <kaboutdata.h>
  4. include <kmessagebox.h>
  5. include <kcmdlineargs.h>

int main (int argc, char *argv[]) {

 KAboutData aboutData( "tutorial1", "Tutorial 2",
     "1.0", "KMessageBox popup",
     KAboutData::License_GPL, "(c) 2006" );
 KCmdLineArgs::init( argc, argv, &aboutData );
 KApplication app;
 KGuiItem guiItem( QString( "Hello" ), QString(),
              QString( "this is a tooltip" ),
              QString( "this is whatsthis" ) );
KMessageBox::questionYesNo( 0, "text", "caption", guiItem );

} If you set up your environment as described in Build/Unstable Version, you can compile this code with

gcc main.cpp -o tutorial1 -I/home/kde-devel/qt-unstable/include/Qt \
-I/home/kde-devel/qt-unstable/include/Qt-Core \
-I/home/kde-devel/qt-unstable/include -I/home/kde-devel/kde/include \
-L/home/kde-devel/kde/lib \
-L/home/kde-devel/qt-unstable/lib -lkdeui -lkdecore -ldl 

and then run it with


If that worked, you may want to use cmake, just like the rest of KDE. Create a file named CMakeLists.txt with this content:

  1. name of the project

project (tutorial1)

  1. find and use the necessary libraries and headers

find_package(KDE4 REQUIRED) include_directories( ${KDE4_INCLUDES} )

  1. compile
  2. using a variable is not really necessary:
  3. using the single line
  4. kde4_add_executable(tutorial1 main.cpp)
  5. does the same, but when you add more stuff to the project,
  6. using the variable makes things a bit easier.

set(tutorial1_SRCS hello.cpp) kde4_add_executable(tutorial1 ${helloSources})

  1. and link properly

target_link_libraries(tutorial1 ${KDE4_KDEUI_LIBS})

Note: This page is about KDE 4. It isn't applicable for KDE 3 development.

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