#include "QApplication" 
#include "QPushButton" 
int main(int argc, char *argv[]) 
{ 
QApplication a(argc, argv); 
QPushButton *button = new QPushButton("Quit"); 
QObject::connect(button, SIGNAL(clicked()),a, 
SLOT(quit())); 
button->show(); 
return a.exec(); 
} 
在main.cpp下的 
报错是