#include <QtGui/QApplication>
#include <QLineEdit>
#include <QPushButton>

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    int ret =0;
    QWidget* w = new QWidget(NULL,Qt::WindowCloseButtonHint);//添加一个关闭按钮，最后只剩下了关闭按钮
    QLineEdit *le = new QLineEdit(w);
    QPushButton* button[20] = {0};
    const char* btnText[20] =
    {
        "7", "8", "9", "+", "(",
        "4", "5", "6", "-", ")",
        "1", "2", "3", "*", "<-",
        "0", ".", "=", "/", "C"
    };

    le->resize(240,30);
    le->move(10,10);
    le->setReadOnly(true);//设置文本框为只读，不输入字符串

    for(int i=0; i<4; i++)
    {
        for(int j=0; j<5; j++)
        {
            button[i*5 + j] = new QPushButton(w);
            button[i*5 + j] ->resize(40,40);//[i*5 + j]是转换为一维来算
            button[i*5 + j]->move(10 + (10 + 40)*j, 50 + (10 + 40)*i);//横坐标移五个，纵坐标移四个
            button[i*5 + j]->setText(btnText[i*5 + j]);
        }
    }

    w->show();
    w->setFixedSize(w->width(), w->height());//要放在show()后，否则是先固定再显示
    ret = a.exec();
    delete w;//记得删除父对象
    return ret;
}