Qt5 Qregexp : why my pattern can't work? - regex

Question

I get this problem When I open a text file, I can't get any matched string. Then I test this pattern: .* but I can either get nothing. I'm sure the text file can be read, and the pattern can be accepted in grep. Thank you.
QList<Nmap_result> ans;
QFile file(path);
if(!file.open(QFile::ReadOnly|QFile::Text))
{
exit(1);
}
QString text = file.readAll();
QRegExp reg(QRegExp::escape(".*"));
reg.indexIn(text);
qDebug()<<reg.capturedTexts().join("|")<<endl<<reg.captureCount()<<endl;
Sorry, I should not use escape. But when I change it like this:
QString text = file.readAll();
qDebug()<<text<<endl;
QRegExp reg("[0-9]");
//reg.indexIn(text); //first bind expr test
reg.exactMatch(text); //second bind expr test
qDebug()<<reg.capturedTexts().join("|!!!!!|")<<endl<<reg.captureCount()<<endl;
I use
reg.indexIn(text);
to bind this string to regexp, it return a number,but when I use the next expr
reg.exeacMatch(text);
I get nothing.

Answer 1

Why do you call QRegExp::escape method ?
Try this instead:
QRegExp reg(".*");
Calling QRegExp::escape, your regular expression becomes similar to this string: "\\.\\*". This string indicates that you want to match a dot immediatly followed by a star. This is not the intented use here: match zero or more characters (.*).