This pattern will match everything directly below your yahoo REPLACE section and non of the good cases above: ^yahoo\.com?(?:(?!\.[a-z]{2}).)*(?:.com?)?$ IE you do not want to include yahoo.fr or yahoo.com.fr or yahoo.co.uk

checks for a continuous string of characters (in this case 7) , but ignores HTML tags we use it in a required feild validator that has auto generated formatting elements

Verbose, somewhat cryptic and very efficient pattern to match all text inside of quotes and MySQL identifier tokens.

Validate phone numbers from Ireland

kljljljjlkjl

Matches everything between '' or "", but not between quotation marks of different types. (?:\")(.?)(?:\")|(?:')(.?)(?:')

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