CODEWITHSUNDEEP
c++regexqt
Farzan Najipour
Farzan Najipour

Reputation: 2503

Qt - how to define regular expression in QString

I've worked on regular expression on Qt , I want to replace all sub string with specific regular expression with image.

my tag struct is combination of < , sml , digits (one or two) and /> and my QString is draftMsg. It will work if I use regular expression once.

for example : "hello <sml7/>" will be change to hello and photo with label 7 in my directory.

Here is my code:

           QRegExp rxlen("<sml(\\d{1,2})/>");
           if (draftMsg.contains(rxlen))
           {
                QString str = rxlen.capturedTexts()[1];
                int index = str.toInt();
                smileyClicked(index-1);

                m_messageEdit->insertHtml(QString("<img src=\":images/smiley/%1_64.png\" width=%2 />")
                                          .arg(index, 2, 10, QLatin1Char('0')).arg(smileyWidth));

                draftMsg = draftMsg.remove(rxlen);
           }

Actually it replace wrongly when I write string like : "hello <sml7/><sml1/>". It will replace both tag to image with label 7.

I searched and I found it. I trying to use captureCount() to keep Regular expression's number and use it.

I've created this function:

void MessageDialog::regInMessage(QString pattern, QString string)
{
    QRegExp regex(pattern);
    if (regex.indexIn(string) < 0) {
        qDebug("Can't find a match.");
        return;
    }
    qDebug() << regex.captureCount();
}

But it gives me "1" instead of two.

Any suggestion to count regular expression on my QString?

Upvotes: 4

Views: 18894

Answers (1)

Amartel
Amartel

Reputation: 4286

Capture - is a string, that matches an expression within brackets. In your regex <sml(\\d{1,2})/> there is only one bracket pair, so the captureCount returns 1. In order to process all entrances of regex in a string you need to do something like this (example from Qt's help):

 QRegExp rx("(\\d+)");
 QString str = "Offsets: 12 14 99 231 7";
 QStringList list;
 int pos = 0;

 while ((pos = rx.indexIn(str, pos)) != -1) {
     list << rx.cap(1);
     pos += rx.matchedLength();
 }
 // list: ["12", "14", "99", "231", "7"]

Also, if you want to replace a string, a good idea would be to use QString & QString::replace ( const QRegExp & rx, const QString & after ).

UPDATE

I'm using QString::replace like this: – afn

QString draftMsg = query.value(0).toString(); QRegExp rx(""); int pos = 0; QStringList list; while ((pos = rx.indexIn(draftMsg, pos)) != -1) { list << rx.cap(1); pos += rx.matchedLength(); } for (int k=0 ; k < list.length() ; ++k) draftMsg.replace(QRegExp(""), ""); – afn

but it doesn't work – afn

Used your code.

In: "hello <sml7/><sml1/>"

Out: "hello <img src=":images/smiley/7.png" width=%2 /><img src=":images/smiley/1.png" width=%2 />"

What were you expecting to get?

Also, all this code can be changed to this:

QString draftMsg = query.value(0).toString();
draftMsg.replace(QRegExp("<sml(\\d{1,2})/>")
                 , "<img src=\":images/smiley/\\1.png\" width=%2 />");

Upvotes: 3

Related Questions