介紹一個小程序，實現16進制和10進制的互轉。其中運用了QString::arg()方法，實現了數字的格式化顯示：數字至少用4位表示；不足四位的，用0補上。

#include "mainwindow.h"#include "ui_mainwindow.h"MainWindow::MainWindow(QWidget *parent) :    QMainWindow(parent),    ui(new Ui::MainWindow){    ui->setupUi(this);}MainWindow::~MainWindow(){    delete ui;}void MainWindow::on_Dec2Hex_clicked(){    QString qstrDec = ui->EdtDec->text();    bool bSuccess;    int iDec = qstrDec.toInt(&bSuccess, 10);    QString qstrHex = QString("%1").arg(iDec, 4, 16, QChar('0'));    ui->EdtHex->setText(qstrHex);}void MainWindow::on_Hex2Dec_clicked(){    QString qstrHex = ui->EdtHex->text();    bool bSuccess;    int iHex = qstrHex.toInt(&bSuccess, 16);    QString qstrDec = QString("%1").arg(iHex, 4, 10, QChar('0'));    ui->EdtDec->setText(qstrDec);}