I am using C++ with QT Creator. I have some code lines which gives me some informations about application. But these are not important for end user. I am using these lines to understand what the program does. I am getting some information from them. So I need 2 different compiling mode: On the first mode, the IDE should compile all the code which exist. On the second mode, IDE should not compile the code lines which I flag ( ! ) them before. So how can I do that?