代碼：QString recstr,tempstr81,tempstr82,tempstr83,tempstr84;recstr = tempstr81.setNum(rect().x())+","+tempstr82.setNum(rect().width())+","+tempstr83.setNum(rect().y())+","+tempstr84.setNum(rect().height());Recvalue->setText(recstr); //Recvalue是一個QLabel；報錯：E:\prooject\qt\chapter7\Geometry\geometry.cpp:74: error: expression cannot be used as a functionrecstr = tempstr81.setNum(rect().x())+","+^覺得代碼沒有問題，是不是Qt版本的問題，還是在沒有添加什么頭文件？已添加的頭文件：#include <QWidget>#include <QLabel>#include <QGridLayout>