Capturing in Regular Expressions

Parenthesis inside regex will be grouped as well as captured.
Let me explain the grouping concept with an example where in you want to validate a decimal part

Eg: Validation for decimal part as given in the below mentioned example

        $input = +345.34f
        $input = ~/([-+]?[0-9]+(\.[0-9]*)?)([cf])$/
        where
                  $1 = /([-+]?[0-9]+(\.[0-9]*)?)    # 345.34
                  $2 = (\.[0-9]*)                            # .34
                  $3 = ([cf])                                  #  f

Notations used in the above example :
1) $1, $2, $3 are grouping data, one can capture the specific data and use it later in the program with $1, $2, $3 etc.,
2) *, + are greedy operators, they match more than what they required, that's why they are called as Greedy Operators
3) ? is a limiting operator which limits the mapping to what ever required
4) [] is a character class
5) $2 lies within $1 even then they both are distinct
6) $ represents the end of the string

Advantages of capturing:
 a) You can capture the data and use the data later in the program
 b) Very useful when we want to grep or capture tricky regex

Disadvantages of unnecessary Capturing:
 a) Waste of memory.
 b) Performance problem.
 c) Regex will be costlier


I hope you have really liked today's topic.

Please share your views with me in case of any any doubts/suggestions. Feel free, don't hesitate :-)

I will be explaining about the Non-Capturing Parenthesis in my next blog. Keep watching my blog.

Thanks for your valuable time. Have a good day :-)