QT5网格布局实现简易计算器

/**********************pro*********************/
QT       += core gui

greaterThan(QT_MAJOR_VERSION, 4): QT += widgets

TARGET = wangge
TEMPLATE = app


SOURCES += main.cpp\
        mainwindow.cpp

HEADERS  += mainwindow.h

FORMS    += mainwindow.ui
/***********************cpp**********************/
#include "mainwindow.h"
#include "ui_mainwindow.h"

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    A="0";
    B="0";
    fuhao=' ';
this->setWindowTitle("calculator");
l = new QLineEdit(this);
l->setText(B);

gridLayout = new QGridLayout();
button1 = new QPushButton("1");
button2 = new QPushButton("2");
button3 = new QPushButton("3");
button4 = new QPushButton("4");
button5 = new QPushButton("5");
button6 = new QPushButton("6");
button7 = new QPushButton("7");
button8 = new QPushButton("8");
button9 = new QPushButton("9");
button0 = new QPushButton("0");
buttonjia = new QPushButton("+");
buttonjian = new QPushButton("-");
buttondengyu = new QPushButton("=");
buttonchen = new QPushButton("*");
buttonchu = new QPushButton("/");
buttonguiling = new QPushButton("C");
buttondian = new QPushButton(".");
gridLayout->addWidget(buttonguiling,2,0,1,5);
gridLayout->addWidget(button1,5,0,1,1);
gridLayout->addWidget(button2,5,1,1,1);
gridLayout->addWidget(button3,5,2,1,1);
gridLayout->addWidget(button4,4,0,1,1);
gridLayout->addWidget(button5,4,1,1,1);
gridLayout->addWidget(button6,4,2,1,1);
gridLayout->addWidget(button7,3,0,1,1);
gridLayout->addWidget(button8,3,1,1,1);
gridLayout->addWidget(button9,3,2,1,1);
gridLayout->addWidget(button0,6,0,1,2);
gridLayout->addWidget(buttonjia,4,3,1,2);