Regular Expressions

Purpose: find patterns in text strings

\d any digit 0 to 9 - character escape or character shorthand
\D any character not a digit (capital = not)?
. "period" match any character - wildcard for a single character; matches everything but a line ending
? means the preceding character is optional
+ one or more
\* zero or more
^ beginning of line
| alternative; OR
$ matches end of line

quantifier (number in curly braces) specifies exactly how many of a character you want

\d{3}-\d{2}-\d{4}

will find a social security pattern: 3 digits hyphen 2 digits hyphen 4 digits

\d{3}-?\d{2}-?\d{4}