QString::arg()//用字符串变量参数依次替代字符串中最小数值

QString i = "iTest";           // current file's number
QString total = "totalTest";       // number of files to process
QString fileName = "fileNameTest";    // current file's name

QString status = QString("Processing file %1 of %2: %3")
                .arg(i).arg(total).arg(fileName);
 style="background-color: #ffffff;">     qDebug() << status ;</span>

 结果就是："Processing file iTest of totalTest: fileNameTest"

First, arg(i) replaces %1. Then arg(total) replaces %2. Finally, arg(fileName) replaces %3.

2、QString::arg ( int a, int fieldWidth = 0, int base = 10, const QChar & fillChar = QLatin1Char( ' ' ) ) const

     16进制输出：fieldWidth表示字符宽度，base表示进制，

QString str;
str = QString("Decimal 63 is %1 in hexadecimal")
        .arg(63, 0, 16);
// str == "Decimal 63 is 3f in hexadecimal"

QLocale::setDefault(QLocale(QLocale::English, QLocale::UnitedStates));
str = QString("%1 %L2 %L3")
        .arg(12345)
        .arg(12345)
        .arg(12345, 0, 16);
// str == "12345 12,345 3039"
//16进制显示，就忽略%L3的L