How to automatically connect qmake to Qt3 after qora5 is installed

When installing Qt4 on Fedora, I used the root user at the beginning, which is slightly different from Ubuntu. Export mvqt-everywhere-opensource-src-4.6.2.tar.gz/tmp # cd/examples # cd

When installing Qt4 on Fedora, I used the root user at the beginning, which is slightly different from Ubuntu.
# Music qt-everywhere-opensource-src-4.6.2.tar.gz/tmp
# Cd/tmp
# Gunzip qt-everywhere-opensource-src-4.6.2.tar.gz
# Tar xvf qt-everywhere-opensource-src-4.6.2.tar
# Cd qt-everywhere-opensource-src-4.6.2
#./Configure
# Gmake (note that gmake is used here)
# Gmake install
Environment variable settings are omitted.

After installing Qt4.6.2 on Fedora 5 according to the preceding steps, set the environment variable. www.linuxidc.com uses qmake to compile the program hello. cpp, the program code is as follows (the first program of C ++ GUI Programming With Qt 4 ):

# Include

# Include

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

{

QApplication app (argc, argv );

QLabel * label = new QLabel ("Hello Qt! ");

Label-> show ();

Return app.exe c ();

}

$ Qmake-project

$ Qmake hello. pro

$ Make

Then an error occurs:

Hello. cpp: 1: 24: error: QApplication: No such file or directory
Hello. cpp: 2: 18: error: QLabel: No such file or directory
Hello. cpp: In function 'int main (int, char **)':
Hello. cpp: 6: error: 'qapplication' was not declared in this scope
Hello. cpp: 6: error: expected '; 'before' app'
Hello. cpp: 7: error: 'qlabel' was not declared in this scope
Hello. cpp: 7: error: 'label' was not declared in this scope
Hello. cpp: 7: error: expected type-specifier before 'qlabel'
Hello. cpp: 7: error: expected '; 'before' qlabel'
Hello. cpp: 9: error: 'app' was not declared in this scope
Hello. cpp: At global scope:
Hello. cpp: 4: warning: unused parameter 'argc'
Hello. cpp: 4: warning: unused parameter 'argv'
Make: *** [hello. o] Error 1

The analysis shows that the header file cannot be found, and all the following errors occur.

Therefore, we guess that the default qmake program in Qt3 is used.

Full-path compilation is as follows:

$/Usr/local/Trolltech/Qt-4.6.2/bin/qmake-project

$/Usr/local/Trolltech/Qt-4.6.2/bin/qmake hello. pro

$ Make

G ++-c-pipe-O2-Wall-W-D_REENTRANT-DQT_NO_DEBUG-DQT_GUI_LIB-DQT_CORE_LIB-DQT_SHARED-I/usr/local/Trolltech/Qt-4.6.2/mkspecs/linux-g + +-I. -I/usr/local/Trolltech/Qt-4.6.2/include/QtCore-I/usr/local/Trolltech/Qt-4.6.2/include/QtGui-I/usr/local/Trolltech/Qt-4.6.2/include -I. -I. -o hello. o hello. cpp
G ++-Wl,-O1-Wl,-rpath,/usr/local/Trolltech/Qt-4.6.2/lib-o hello. o-L/usr/local/Trolltech/Qt-4.6.2/lib-lQtGui-L/usr/local/Trolltech/Qt-4.6.2/lib-L/usr/X11R6/lib-lQtCore-lpthread

$ Ls

Hello. cpp hello. o hello. pro Makefile

The executable program hello, compiled successfully, run also successful, so concluded that the default qmake is not what we need/usr/local/Trolltech/Qt-4.6.2/bin/qmake.

The following describes how many qmake programs are available in the following system:
$ Locate qmake

/Usr/bin/qmake
/Usr/include/kdevelop/buildtools/parsers/qmake

/Usr/lib/qt-3.3/bin/qmake

// Usr/local/Trolltech/Qt-4.6.2/bin/qmake

Only list part of what we need. Well, we can see that there is a qt-3.3 of qmake among them, and/usr/bin in the environment variable, the first/usr/bin/qmake may be the error qmake. Let's take a look at/usr/bin/qmake:

$ Which qmake

/Usr/bin/qmake

We can see that this is the default qmake

$ Ls-l/usr/bin/qmake

Rwxrwxrwx 1 root 23 Mar 23/usr/bin/qmake-> ../lib/qt-3.3/bin/qmake

$ File/usr/bin/qmake
/Usr/bin/qmake: symbolic link to '../lib/qt-3.3/bin/qmake'

See, this is a soft link to qmake in the qt-3.3. You just need to modify the position it points.

$ Su

Password:

# Ln-s/usr/local/Trolltech/Qt-4.6.2/bin/qmake/usr/bin/qmake
Ln: creating symbolic link '/usr/bin/qmake' to '/usr/local/Trolltech/Qt-4.6.2/bin/qmake': File exists

# Ln-s/usr/local/Trolltech/Qt-4.6.2/bin/qmake/usr/bin/qmake1

# Ls/usr/bin/qmak *

/Usr/bin/qmake/usr/bin/qmake1

# Mv/usr/bin/qmake1/usr/bin/qmake
Mv: overwrite '/usr/bin/qmake '? Yes

# Ls/usr/bin/qmak *
/Usr/bin/qmake

# Ls-al/usr/bin/qmake
Lrwxrwxrwx 1 root 39 Mar 25/usr/bin/qmake->/usr/local/Trolltech/Qt-4.6.2/bin/qmake

Now, the Makefile is deleted and re-compiled:

$ Qmake-project
QFileInfo: absolutePath: Constructed with empty filename
$ Qmake hello. pro
$ Make
G ++-c-pipe-O2-Wall-W-D_REENTRANT-DQT_NO_DEBUG-DQT_GUI_LIB-DQT_CORE_LIB-DQT_SHARED-I/usr/local/Trolltech/Qt-4.6.2/mkspecs/linux-g + +-I. -I/usr/local/Trolltech/Qt-4.6.2/include/QtCore-I/usr/local/Trolltech/Qt-4.6.2/include/QtGui-I/usr/local/Trolltech/Qt-4.6.2/include -I. -I. -o hello. o hello. cpp
G ++-Wl,-O1-Wl,-rpath,/usr/local/Trolltech/Qt-4.6.2/lib-o hello. o-L/usr/local/Trolltech/Qt-4.6.2/lib-lQtGui-L/usr/local/Trolltech/Qt-4.6.2/lib-L/usr/X11R6/lib-lQtCore-lpthread
$ Ls
Hello. cpp hello. o hello. pro Makefile

Solve the problem.