http://stackoverflow.com/questions/34674917/is-regex-a-costly-operation-it-seems-atleast

http://stackoverflow.com/questions/34674917/is-regex-a-costly-operation-it-seems-atleast

Matches phone #s (aaa) bbb-cccc aaa bbb cccc aaabbbcccc and such.

Trying to understand the two digit lookup.

Validates Israeli phone numbers. Accounts for the presence/absence of the 972 country code (with or without the plus sign or parentheses), and the proper formatting of area codes based on the presence/absence of the country code. Allows subdivision using spaces, dashes, periods, or no subdivision.

Use for Ukraine cities telephon number (not mobile). Example: 0442565656 (044)1565656 (05656)156-56-56 156-56-56

username is 4-32 characters long no _,- or . at the beginning no _ or _. or . or .. or .- or _- inside no _,- or . at the end ^(?=.{4,32}$)(?![.-])(?!.*[.]{2})[a-zA-Z0-9.-]+(?<![.])$...

a robust pattern to remove ordinal suffixes from numbers, eg. '22nd'->'22' supports: singles: 1st, 2nd, 3rd, 4th teens: 11th, 12th, 13th, 14th

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