PHP Notes 7 Lakshman Gupta 9:47 AM 10/8/2019 PHP Tutorial Regular Expressions Regular expressions, a powerful tool for manipulating text and data, are found in scripting languages, editors, programming environments, and specialized tools. Special characters: "/" "-" "^" "." "\" "^" "$" "*" "+" "(" ")" Equivalent Description or Meaning Examples /abc/ search for substring "abc" /[akt]/ search for one of "a", "k" or "t". /[^akt]/ true if string do not have any one of "a", "k" or "t". /[0-4]/ /[01234]/ search for one of "0", "1", "2", "3" or "4" /.../i Case insensitive * Zero or more /abck*pqr/ + One or more /abck+pqr/ \d [0-9] Any decimal digit [0123456789] \D Any character that is not a decimal digit \w [0-9A-Za-z_] Alphanumerics and underscore...