@SGaist said: Hi, What should the output look like ? if is something like "$0.0" ui->label->setText(QString("$%1").arg(APP_VERSION, 2, 'f', 1); would be way simpler and clean Sorry for the late reply. No, the result should be ''0.0": the $ is used only for the variable like in bash. I just wanted to replace $APP_VERSION string inside label by 0.0 using BASH_REPL_WCS. is there anything wrong with the preprocessor? if not, how to do it using the high-level Qt method?