Regular Expressions

Regular expressions

A formal language for specifying text strings

rules

Disjunctions:
Letters inside square brackets[]: [A-Z]
pipe |: a|b|c
Negation in Disjunction: ^Ss

?: When placed after a character or a group, the question mark makes it optional, meaning that the character or group can occur zero or one time.
When placed after a quantifier, such as , +, or ?, it modifies the quantifier to be non-greedy or lazy. A non-greedy quantifier matches as few characters as possible, while a greedy quantifier matches as many characters as possible. :0 or more of previous char
+:1 or more of previous char
.:any char

Anchors:
^: The begining. $: The end.