RegexReplace

[Cesar]

QString QRegexReplace(coQString str, const QString& regex
    , const QString& replace, QRegularExpression::PatternOption flag)
{
    QRegularExpression re(regex, flag);
    return str.replace(re, replace);
}

QString s = "111111111111111111111111111111111111111110";
 s = QRegexReplace(s, ".{6}", "|$0");

My function is replacing s to |$0|$0|$0|$0|$0|$0|$0

How i could get the same result as seen on: https://regex101.com/r/bsgCKf/1
Im trying to get s to |111111|111111|111111|111111|111111|111111|111110

[JonB]

@Cesar
Good question! I cannot test for Qt, but try

s = QRegexReplace(s, "(.{6})", "|\\1");

?

https://regex101.com/r/YOrWq9/1

[Cesar]

This does work, but i would like to understand why mregex isn't working?

[JonB]

@Cesar
I don't know, your way is not supported by the regular expressions used in Qt is all I can say. The one I gave you works in PCRE (PHP < 7.3), maybe that is what Qt uses.

[DerReisende]

@JonB
From the Qt5/Qt6 doc:
„QRegularExpression implements Perl-compatible regular expressions.“

[JonB]

@DerReisende
The problem is that is apparently/evidently not true, or not sufficiently accurate!

On the regex site they offer "flavor" of PCRE2 (PHP >= 7.3) and their "Help" for that states "Perl PCRE2". And if you use |$0 for Substitution that gives the OP's desired result of |111111|111111|111111|111111|111111|111111|111110. You can see this from the link the OP supplied: https://regex101.com/r/bsgCKf/1

That would be fine if OP then reported using that in Qt as QRegexReplace(s, ".{6}", "|$0"); delivered same. The problem is it does not! He says that gives him |$0|$0|$0|$0|$0|$0|$0, i.e. $0 is not being recognised/substituted. That can be seen if e.g. you change "flavor" over to Python, which does not recognise $0.

I found that did work in various "flavors" with parentheses-capture and \1, see my https://regex101.com/r/YOrWq9/1, hence my suggestion OP try QRegexReplace(s, "(.{6})", "|\\1"); in Qt, which he confirms "This does work"....