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What is the difference between encasing part of a regular expression in () (parentheses) and doing it in [] (square brackets)?
How does this:
[a-z0-9]
differ from this:
(a-z0-9)
?
[]denotes a character class.()denotes a capturing group.[a-z0-9]— One character that is in the range ofa-zOR0-9(a-z0-9)— Explicit capture ofa-z0-9. No ranges.a— Can be captured by[a-z0-9].a-z0-9— Can be captured by(a-z0-9)and then can be referenced in a replacement and/or later in the expression.