std::regex_error exception thrown at runtime

Question

Given that this code works:

regex r1{ "fish"s };
smatch m1;
if (regex_search("I love fish and chips"s, m1, r1))
    cout << m1[0] << endl;

I believe that VS2015 supports regular expressions. However, initialization of this regular expression object:

regex r{ R"(\d{2,3}(-\d\d) { 2 })" };

throws a std::regex_error exception. What's wrong with the initialization?

Try to replace { 2 } (plus the space left from {) with {2} or - with \-. — Sebastian Simon
– Sebastian Simon, Commented Mar 30, 2015 at 17:28
@Xufox wow, dude, you are absolutely correct! This part of the regexp (-\d\d) { 2 } needed to be written as (-\d\d){2} — Nikolay Zhulikov
– Nikolay Zhulikov, Commented Mar 30, 2015 at 17:33
@Xufox thank you :) I spent a hour on this tiny tiny mistake. — Nikolay Zhulikov
– Nikolay Zhulikov, Commented Mar 30, 2015 at 17:35
@NikolayZhulikov: Just for your knowledge, GCC 4.9.0 supports <regex> — Bill Lynch
– Bill Lynch, Commented Mar 30, 2015 at 18:03

Sebastian Simon · Accepted Answer · 2015-04-03 14:09:57Z

3

So, yeah, as mentioned in the comments:

(\d{2,3}(-\d\d) { 2 })

should be

(\d{2,3}(-\d\d){2})

otherwise the {2} relates to the space instead of the (-\d\d), and other weird things might possibly happen as well…

answered Mar 30, 2015 at 17:36

Sebastian Simon

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Comments

Federico Piazza · Accepted Answer · 2015-03-30 17:36:37Z

2

You have a typo in your regex. Change this:

regex r{ R"(\d{2,3}(-\d\d) { 2 })" };

To:

regex r{ R"(\d{2,3}(-\d\d){2})" };

answered Mar 30, 2015 at 17:36

Federico Piazza

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