**
Kvalley Computers and Internet -- RegEx Evaluator**

Symbol | Function |
---|---|

^ | Only match the beginning of a string. "^A" matches first "A" in "An A+ for Anita." |

$ | Only match the ending of a string. "t$" matches the last "t" in "A cat in the hat" |

\b | Matches any word boundary. "ly\b" matches "ly" in "possibly tomorrow." |

\B | Matches any non-word boundary. |

Symbol | Function |
---|---|

Alphanumeric | Matches alphabetical and numerical characters literally. |

\n | Matches a new line. |

\f | Matches a form feed. |

\r | Matches carriage return. |

\t | Matches horizontal tab. |

\v | Matches vertical tab. |

\? | Matches ? |

\* | Matches * |

\+ | Matches + |

\. | Matches . |

\| | Matches | |

\{ | Matches { |

\} | Matches } |

\\ | Matches \ |

\[ | Matches [ |

\] | Matches ] |

\( | Matches ( |

\) | Matches ) |

\xxx | Matches the ASCII character expressed by the octal
number xxx. "\50" matches "(" or chr (40). |

\xdd | Matches the ASCII character expressed by the hex
number dd. "\x28" matches "(" or chr (40). |

\uxxxx | Matches the ASCII character expressed by the
UNICODE xxxx. "\u00A3" matches "£". |

Symbol | Function |
---|---|

[xyz] | Match any one character enclosed in the character
set. "[a-e]" matches "b" in "basketball". |

[^xyz] | Match any one character not enclosed in the character
set. "[^a-e]" matches "s" in "basketball". |

. | Match any character except \n. |

\w | Match any word character. Equivalent to [a-zA-Z_0-9]. |

\W | Match any non-word character. Equivalent to [^a-zA-Z_0-9]. |

\d | Match any digit. Equivalent to [0-9]. |

\D | Match any non-digit. Equivalent to [^0-9]. |

\s | Match any space character. Equivalent to [ \t\r\n\v\f]. |

\S | Match any non-space character. Equivalent to [^ \t\r\n\v\f]. |

Symbol | Function |
---|---|

{x} | Match exactly x occurrences of a regular
expression. "\d{5}" matches 5 digits. |

{x,} | Match x or more occurrences of a regular
expression. "\s{2,}" matches at least 2 space characters. |

{x,y} | Matches x to y number of occurrences of a regular
expression. "\d{2,3}" matches at least 2 but no more than 3 digits. |

? | Match zero or one occurrences. Equivalent to {0,1}. "a\s?b" matches "ab" or "a b". |

* | Match zero or more occurrences. Equivalent to {0,}. |

+ | Match one or more occurrences. Equivalent to {1,}. |

Symbol | Function |
---|---|

() | Grouping a clause to create a clause. May be nested. "(ab)?(c)" matches "abc" or "c". |

| | Alternation combines clauses into one regular
expression and then matches any of the individual clauses. "(ab)|(cd)|(ef)" matches "ab" or "cd" or "ef". |

Symbol | Function |
---|---|

()\n | Matches a clause as numbered by the left parenthesis. "(\w+)\s+\1" matches any word that occurs twice in a row, such as "hubba hubba." |

(?!) | Negative Lookahead. "^(?!ver)v" matches any word starting with"v" except if the word starts with "ver". |