为什么有这样的警告
#include <QtGui>class QApplication;class QDialog;int main(int argc, char **argv){ QApplication app(argc, argv); QDialog *one = new QDialog(0); QDialog *two = new QDialog(one); one->show(); return app.exec();}//main.cpp:12: warning: unused variable `QDialog*two'为什么有这样的警告?