Getting Started with qmake
This tutorial teaches you the basics of qmake. The other topics in this manual contain more detailed information about using qmake.
Starting Off Simple
Let's assume that you have just finished a basic implementation of your application, and you have created the following files:
- hello.cpp
- hello.h
- main.cpp
You will find these files in the examples/qmake/tutorial
directory of the Qt distribution. The only other thing you know about the setup of the application is that it's written in Qt. First, using your favorite plain text editor, create a file called hello.pro
in examples/qmake/tutorial
. The first thing you need to do is add the lines that tell qmake about the source and header files that are part of your development project.
We'll add the source files to the project file first. To do this you need to use the SOURCES variable. Just start a new line with SOURCES +=
and put hello.cpp after it. You should have something like this:
SOURCES += hello.cpp
We repeat this for each source file in the project, until we end up with the following:
SOURCES += hello.cpp SOURCES += main.cpp
If you prefer to use a Make-like syntax, with all the files listed in one go you can use the newline escaping like this:
SOURCES = hello.cpp \ main.cpp
Now that the source files are listed in the project file, the header files must be added. These are added in exactly the same way as source files, except that the variable name we use is HEADERS.
Once you have done this, your project file should look something like this:
HEADERS += hello.h SOURCES += hello.cpp SOURCES += main.cpp
The target name is set automatically. It is the same as the project filename, but with the suffix appropriate for the platform. For example, if the project file is called hello.pro
, the target will be hello.exe
on Windows and hello
on Unix. If you want to use a different name you can set it in the project file:
TARGET = helloworld
The finished project file should look like this:
HEADERS += hello.h SOURCES += hello.cpp SOURCES += main.cpp
You can now use qmake to generate a Makefile for your application. On the command line, in your project directory, type the following:
qmake -o Makefile hello.pro
Note: If you installed Qt via a package manager, the binary may be qmake6
.
Then type make
or nmake
depending on the compiler you use.
For Visual Studio users, qmake can also generate Visual Studio project files. For example:
qmake -tp vc hello.pro
Making an Application Debuggable
The release version of an application does not contain any debugging symbols or other debugging information. During development, it is useful to produce a debugging version of the application that has the relevant information. This is easily achieved by adding debug
to the CONFIG variable in the project file.
For example:
CONFIG += debug HEADERS += hello.h SOURCES += hello.cpp SOURCES += main.cpp
Use qmake as before to generate a Makefile. You will now obtain useful information about your application when running it in a debugging environment.
Adding Platform-Specific Source Files
After a few hours of coding, you might have made a start on the platform-specific part of your application, and decided to keep the platform-dependent code separate. So you now have two new files to include into your project file: hellowin.cpp
and hellounix.cpp
. We cannot just add these to the SOURCES
variable since that would place both files in the Makefile. So, what we need to do here is to use a scope which will be processed depending on which platform we are building for.
A simple scope that adds the platform-dependent file for Windows looks like this:
win32 { SOURCES += hellowin.cpp }
When building for Windows, qmake adds hellowin.cpp
to the list of source files. When building for any other platform, qmake simply ignores it. Now all that is left to be done is to create a scope for the Unix-specific file.
When you have done that, your project file should look something like this:
CONFIG += debug HEADERS += hello.h SOURCES += hello.cpp SOURCES += main.cpp win32 { SOURCES += hellowin.cpp } unix { SOURCES += hellounix.cpp }
Use qmake as before to generate a Makefile.
Stopping qmake If a File Does Not Exist
You may not want to create a Makefile if a certain file does not exist. We can check if a file exists by using the exists() function. We can stop qmake from processing by using the error() function. This works in the same way as scopes do. Simply replace the scope condition with the function. A check for a file called main.cpp looks like this:
!exists( main.cpp ) { error( "No main.cpp file found" ) }
The !
symbol is used to negate the test. That is, exists( main.cpp )
is true if the file exists, and !exists( main.cpp )
is true if the file does not exist.
CONFIG += debug HEADERS += hello.h SOURCES += hello.cpp SOURCES += main.cpp win32 { SOURCES += hellowin.cpp } unix { SOURCES += hellounix.cpp } !exists( main.cpp ) { error( "No main.cpp file found" ) }
Use qmake as before to generate a makefile. If you rename main.cpp
temporarily, you will see the message and qmake will stop processing.
Checking for More than One Condition
Suppose you use Windows and you want to be able to see statement output with qDebug()
when you run your application on the command line. To see the output, you must build your application with the appropriate console setting. We can easily put console
on the CONFIG
line to include this setting in the Makefile on Windows. However, let's say that we only want to add the CONFIG
line when we are running on Windows and when debug
is already on the CONFIG
line. This requires using two nested scopes. First create one scope, then create the other inside it. Put the settings to be processed inside the second scope, like this:
win32 { debug { CONFIG += console } }
Nested scopes can be joined together using colons, so the final project file looks like this:
CONFIG += debug HEADERS += hello.h SOURCES += hello.cpp SOURCES += main.cpp win32 { SOURCES += hellowin.cpp } unix { SOURCES += hellounix.cpp } !exists( main.cpp ) { error( "No main.cpp file found" ) } win32:debug { CONFIG += console }
That's it! You have now completed the tutorial for qmake, and are ready to write project files for your development projects.
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