QRegExp. Extract sentence containing keyword to the end

mandruk1331

Hello,

I have a text and would like to extract all of the strings containing a keyword until the end of the sentence.
Here what I have came up with:
Sample text:

sddadsadsadsa: [error] dsadsdasdsads
sddadsadsadsa: [error] dsadsdasdsads
sdadsadadsad
sddadsadsadsa: [error] dsadsdasdsads

Code:

   QRegExp rx;
   rx.setPattern("\\[error].*");
   rx.setPatternSyntax(QRegExp::RegExp);
   rx.indexIn(data);
   QStringList list = rx.capturedTexts();

I have tried using this syntax in Notepad++ and everything worked nicely. But here I am getting an empty string list. Could you tell me what am I doing wrong?

Chris Kawa

It's recommended to use QRegularExpression instead of QRegExp in new code.
Notepad++ automatically applies the pattern to each line. In Qt you need to do that yourself. You can use a handy iterator returned by globalMatch() function for that.
\ is an escape character in C++. If you want to use that character in a string you need to escape it i.e. double it \\ or use the C++ raw string literal.
If you want to get the text after a keyword you need to actually capture it i.e. use capture group (.*).

So a code for your example could look like this:

QRegularExpression rx(R"(.*\[error\](.*))");
auto it = rx.globalMatch(data);
while(it.hasNext())
{
    auto match = it.next();
    if (match.lastCapturedIndex() == 1)
        qDebug() << match.capturedView(1);
}

or

QRegularExpression rx(".*\\\[error\\\](.*)");

if you don't want to use the raw string literal.

mandruk1331

Hello,

I have tried your variant it returns string which I do not need. I am parsing out an HTML code of the page. When I run you variant it returns all kind of string, and I only need the sentence where the "[error]" key word is present.

Update:
This variant of RegExp works like a charm:

\\\[error\\\](.*)

Thank you for your time. The issue has been resolved