Basic Regex Cheat Sheet

Symbols

• “^” : Matches the beginning of the string.
• “$” : Matches the end of the string.
• “ . ” : Matches any single character, except for line breaks.
• “ * “ : Matches the preceding expression zero or more times.

Characters

• “ \d “ : Any single digit character. Ex: 1, 2, 3, …
• “ \w “ : Any word character (alphanumeric & underscore). Ex: a, A, b, B, …
• “ \W “ : Any character that is not a word character. Ex: *,-,+,=
• “ \D “ : Any character that is not a digit . Ex: a,B,+
• “ \s “ : Whitespace

Classes

• “ [abc] ” : Character Set: Any single character from the character within the brackets. Values: a, b, c
• “ [a-z] “ : Character Set: Character range, start from “a” to “z”, all lowercase letters.Ex: a,b,c, …
• “ [a-z]+” : One or more of any of the characters in the set.
• “ [^a-z] ”: Inside a character set, the ^ is used for negation. In this example, match anything that is NOT a lowercase letter.

Logic

• “ | “ : OR operand. Ex: 22|33
• “ ( … ) ” : Capturing group. Ex : B(arman|eer)
• “ (?: … ) ” : Non-capturing group. Ex: B(?:arman|eer)

Quantifiers

• “ +“ : Matches the preceding expression 1 or more times.
• “ {3} “ : Exactly three times. Ex: d{3} -> 123, 321
• “ ? ” : Preceding expression is optional (Matches 0 or 1 times).