How to convert regex Pattern from C# to C++?

Question

I’m trying to use C++ regex but I’m having some difficulties, one of them is that Pattern was in a C#code, and I know practically nothing of regex in C++, and so the code does not work as it should in C++

Here’s the excerpt of the code that doesn’t work as it should:

if (!std::regex_match("BLUS31029", std::regex("^B[LC][JUEAK][SM]\d{5}$")))
    print_error("Invalid game id: " + game_id);
else
    ::id_ = game_id;
}

PS: I already changed the regex_match for regex_search and yet it didn’t work

Answer 1

In the string of the regular expression, the character \d is recognized by the compiler so incorrect as a exhaust (escape sequence).

In several languages, the backslash \ followed by a symbol, is used to represent characters other than may be printed or have special meanings.

Example: \n represents the action "New Line".

To represent the backslash character, it is necessary to use two bars \\, to indicate to the compiler that it is not a escape sequence.

Depending on the configuration of Visual Studio (2019), during compilation, it must have issued a warning stating a sequence not recognized:

Warning C4129: ’d': unrecognized Character escape

The excerpt from the program in the question, with the corrected regular expression, is as follows::

if (!std::regex_match("BLUS31029", std::regex("^B[LC][JUEAK][SM]\\d{5}$")))
    print_error("Invalid game id: " + game_id);
else
    ::id_ = game_id;
}