Qt regex not matching

Question

Qt's regex (C++) is not working as I expect. For example, in the following line (spaces as full stops)

.....mRNA............complement(join(<85666..86403,86539..>86727))

"mRNA" is not matched by:

QRegExp rxItem("^\\s{5}(\\w+)") ;

But is matched by the following:

QRegExp rxItem("\\s{4}(\\w+)") ;

So it looks as if the start of the line and the first space is not being recognised for some reason. I checked-out the Qt documentation for QRegExp and as far as I can tell "^" signifies the start of a line and \s is space as in Perl.

Any ideas?

Cheers

Does the number of spaces matter to you? If not then just match zero or more `\s*(\w+)` or one or more `\s+(\w+)`. — trojanfoe, Nov 21 '11 at 11:47
Looks like a bug then as your match string looks good to me. — trojanfoe, Nov 21 '11 at 11:52

score 4 · Accepted Answer · answered Nov 21 '11 at 12:13

The following code:

#include <QtCore/QRegExp>
#include <QtCore/QString>
#include <QtCore/QDebug>

int main(int argc, char *argv[])
{
    QString test = "     mRNA            complement(join(<85666  86403,86539  >86727))";
    QRegExp rxItem( "^\\s{5}(\\w+)" );

    if( rxItem.indexIn( test ) != -1 )
    {
        qDebug() << "Matched" << rxItem.cap( 1 );
    }
    else
    {
        qDebug() << "No match";
    }

    return 0;
}

displays

Matched "mRNA"

So it seems to be working. Did you maybe treat a result of 0 returned by indexIn as error?

Thanks Tim. I was looking for values > 0 returned by indexIn before printing captured texts. Your way works. — nrhorner, Nov 21 '11 at 12:36

Qt regex not matching

1 Answers1