c++ - Convert an int to a QString with zero padding (leading zeroes)


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I want to "stringify" a number and add zero-padding, like how printf("%05d") would add leading zeros if the number is less than 5 digits.



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    Use this:

    QString number = QString("%1").arg(yourNumber, 5, 10, QChar('0'));
    

    5 here corresponds to 5 in printf("%05d"). 10 is the radix, you can put 16 to print the number in hex.


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    QString QString::rightJustified ( int width, QChar fill = QLatin1Char( ' ' ), bool truncate = false ) const

    int myNumber = 99;
    QString result;
    result = QString::number(myNumber).rightJustified(5, '0');
    

    result is now 00099


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    The Short Example:

    int myNumber = 9;
    
    //Arg1: the number
    //Arg2: how many 0 you want?
    //Arg3: The base (10 - decimal, 16 hexadecimal - if you don't understand, choose 10)
    //      It seems like only decimal can support negative numbers.
    QString number = QString("%1").arg(myNumber, 2, 10, QChar('0')); 
    
    Output will be: 09
    

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    Try:

    QString s = s.sprintf("%08X",yournumber);
    

    EDIT: According to the docs at http://qt-project.org/doc/qt-4.8/qstring.html#sprintf:

    Warning: We do not recommend using QString::sprintf() in new Qt code. Instead, consider using QTextStream or arg(), both of which support Unicode strings seamlessly and are type-safe. Here's an example that uses QTextStream:

    QString result;
    QTextStream(&result) << "pi = " << 3.14;
    // result == "pi = 3.14"
    

    Read the other docs for features missing from this method.


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    I was trying this (which does work, but cumbersome).

    QString s;
    s.setNum(n,base);
    s = s.toUpper();
    presision -= s.length();
    while(presision>0){
        s.prepend('0');
        presision--;
    }
    

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    I use a technique since VB 5

    QString theStr=QString("0000%1").arg(theNumber).right(4);
    

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    function zeroPad(num, places) {
            num = num.toString().toUpperCase();
            return num.length < places ? zeroPad("0" + num, places) : num;
        }
    

    I use this recursive function to pad zero!