[Solved] regex not working in qt
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Hello everyone,
I am trying to use regex in qt. I want to use regex for matching URLs. I am using this regex : http://regexr.com/3acbl
But I got warnings and it didn't work :
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warning: unknown escape sequence: '/'
in QString regexp = "(http(s)?://.)?(www.)?[-a-zA-Z0-9@:%.+~#=]{2,256}.[a-z]{2,6}\b([-a-zA-Z0-9@:%+.~#?&//=]*)";
^
warning: unknown escape sequence: '/'
warning: unknown escape sequence: '.'
warning: unknown escape sequence: '+'
warning: unknown escape sequence: '.'
warning: unknown escape sequence: '+'
@When I googled these, I got to know that c++ does not recognizes these as escape sequence and require one extra backslash "" there.
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QString regexp = "(http(s)?:\/\/.)?(www\.)?[-a-zA-Z0-9@:%.\+~#=]{2,256}\.[a-z]{2,6}\b([-a-zA-Z0-9@:%\+.~#?&//=]*)";
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Although warnings went after using one extra backslash but it is still not matching URLs.Regards,
Ashish Bansal
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It looks like you should have a look to the documentation of "QRegExp":http://doc.qt.io/qt-5/qregexp.html and "QRegularExpression":http://doc.qt.io/qt-5/qregularexpression.html or the "regexp example":http://doc.qt.io/qt-5/qtwidgets-tools-regexp-example.html
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Hi,
Out of curiosity, why the regexp ? Wouldn't QUrl be more adequate ?
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Hi SGaist,
I am not able to validate URI using QUrl::isValid(). It does not checks the syntax of the URL. It just checks the encoding errors like if I my URL is
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http://foo.bar/%3
@It returns false and if URL is
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foo://bar or foo://bar/baz
@It returns true.
Then How can I use it to validate the URL?
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Hi koahnig,
Can you please explain it a bit?
EDIT:
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The C++ compiler transforms backslashes in strings. To include a \ in a regexp, enter it twice, i.e. \. To match the backslash character itself, enter it four times, i.e. \\.
@I already have corrected this. Then where's the mistake?
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[quote author="ashishbansal" date="1423288352"]Hi koahnig,
Can you please explain it a bit?
EDIT:
@
The C++ compiler transforms backslashes in strings. To include a \ in a regexp, enter it twice, i.e. \. To match the backslash character itself, enter it four times, i.e. \\.
@I already have corrected this. Then where's the mistake?[/quote]
Your post requires quite a number of assumptions what you are trying to do.My impression was that you simply trying to store some syntax of regexp in a QString. However, you would need an engine such as QRegExp or QRegularExpressions.
There you should find also all things for C++ string handling.Therefore I thought that you should know about QRegExp.
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Well for the sake of simplicity, I hadn't posted the whole code. I am already using QRegExp in my code.
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QString url = "http://foo.bar";QString regexp = "(http(s)?:\/\/.)?(www\.)?[-a-zA-Z0-9@:%.\+~#=]{2,256}\.[a-z]{2,6}\b([-a-zA-Z0-9@:%\+.~#?&//=]*)";
QRegExp rx(regexp);
rx.indexIn(url);if(rx.cap(0).length() != 0){
//url passed validation test
....
}
@
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OK, sorry for my wrong assumption.
I would recommend the QRegExp example for checking, if you are not doing this already. I am using it for fast checks of reg exp.
I have tried with your example, but I could not verify any of your examples. The exampel gives you also the string with proper escape sequences for your code. However, I had to reverse your escapes. Probably there is the problem.
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"This":https://gist.github.com/dperini/729294 might interest you then
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[quote author="koahnig" date="1423307221"]OK, sorry for my wrong assumption.
I would recommend the QRegExp example for checking, if you are not doing this already. I am using it for fast checks of reg exp.
I have tried with your example, but I could not verify any of your examples. The exampel gives you also the string with proper escape sequences for your code. However, I had to reverse your escapes. Probably there is the problem.
[/quote]Hey thanks for referring to that tool. Actually I missed one backslash on "\b" , that's why it was not working but that tool gave me correct escaped string on passing my normal js regex :)
[quote author="SGaist" date="1423344819"]"This":https://gist.github.com/dperini/729294 might interest you then[/quote]
Well that regex is most popular regex on the Google but I don't know why it does not work for me. You can check it here : http://regexr.com/3acgt
Anyway Thanks![In case someone needs regex for URL, you can try this out]
Finally I have used this basic regex for URL validation:
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^(((http|ftp)(s?)://)|(www.))(([a-zA-Z0-9-.]+(.[a-zA-Z0-9-.]+)+)|localhost)(/?)([a-zA-Z0-9-.?,'/\+&%$#_])?([\d\w./%+-=&?:\"',|~;])$
@Escaped Pattern for using it in C++:
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"^(((http|ftp)(s?)\:\/\/)|(www\.))(([a-zA-Z0-9\-\.]+(\.[a-zA-Z0-9\-\.]+)+)|localhost)(\/?)([a-zA-Z0-9\-\.\?\,\'\/\\\+&%\$#_])?([\d\w\.\/\%\+\-\=\&\?\:\\\"\'\,\|\~\;])$"
@
