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C ++ 11 - regex matching

I am extracting information from a string using regex.

  auto version = { // comments shows the expected output
    // version         // output : (year, month, sp#, patch#)
    "2012.12",         // "2012", "12", "", ""
    "2012.12-1",       // "2012", "12", "", "1" 
    "2012.12-SP1",     // "2012", "12", "SP1", "" 
    "2012.12-SP2-1",   // "2012", "12", "SP2", "1" 
    "I-2013.12-2",     // "2013", "12", "", "2"
    "J-2014.09",       // "2014", "09", "", ""
    "J-2014.09-SP2-1", // "2014", "09", "SP2", "1"
};

I have the following regex:

    //                  J   -  2014       .  09      -  SP2      -  1  
std::regex regexExpr("[A-Z]?-?([0-9]{4})\\.([0-9]{2})-?(SP[1-9])?-?([1-9])?.*");

and it seems to work well . I'm not very sure about this as I don't have much experience with regex. Is the regex correct and can it be improved?

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You can simply use \w{2,}|\d

as your regex, which matches any combination of word characters of length 2 or more ( \w{2,}

) (to avoid matching j

at the beginning of some lines) or numbers using length 1 ( \d

) (to match 1 at the end of some lines)!

Demo



You can use a class template sub_match

for this purpose:

A class template is sub_match

used by the regular expression engine to denote character sequences matching marked subexpressions. A match is a [begin, end] pair in the target range that matches the regular expression, but with additional observer functions to improve the clarity of the code.

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