Differences

This shows you the differences between two versions of the page.

--- system:regex:regex_notation [2017/09/19 10:58]
smayr created
+++ system:regex:regex_notation [2018/04/13 11:52] (current)
smayr [Regex Quick Reference]
@@ Line 2: / Line 2: @@
 == Regex Quick Reference ==
-[abc]     A single character: a, b or c
+^ Symbol       ^ Description ^
-[^abc]     Any single character but a, b, or c
+| [abc]        | A single character: a, b or c |
-[a-z]     Any single character in the range a-z
+| [<nowiki>^</nowiki>abc]       | Any single character but a, b, or c |
-[a-zA-Z]     Any single character in the range a-z or A-Z
+| [a-z]        | Any single character in the range a-z |
-^     Start of line
+| [a-zA-Z]     | Any single character in the range a-z or A-Z |
-$     End of line
+| <nowiki>^</nowiki>            | Start of line |
-\A     Start of string
+| .            | Any single character |
-\z     End of string
+| \s           | Any whitespace character |
-.     Any single character
+| \S           | Any non-whitespace character |
-\s     Any whitespace character
+| \d           | Any digit |
-\S     Any non-whitespace character
+| \D           | Any non-digit |
-\d     Any digit
+| \w           | Any word character (letter, number, underscore) |
-\D     Any non-digit
+| \W           | Any non-word character |
-\w     Any word character (letter, number, underscore)
+| (...)        | Capture everything enclosed |
-\W     Any non-word character
+| (a<nowiki>|</nowiki>b)        | a or b |
-\b     Any word boundary character
+| a?           | Zero or one of a |
-(...)     Capture everything enclosed
+| a*           | Zero or more of a |
-(a|b)     a or b
+| a+           | One or more of a |
-a?     Zero or one of a
+| a{3}         | Exactly 3 of a |
-a*     Zero or more of a
+| a{3,}        | 3 or more of a |
-a+     One or more of a
+| a{3,6}       | Between 3 and 6 of a |
-a{3}     Exactly 3 of a
-a{3,}     3 or more of a
-a{3,6}     Between 3 and 6 of a
-options:
+General Tokens:
-  i case insensitive
+^ Symbol       ^ Description ^
-  m make dot match newlines
+| \n           | Newline |
-  x ignore whitespace in regex
+| \r           | Carriage return |
-  o perform #{...} substitutions only once
+| \t           | Tab |
+| \f           | Form-feed |
+| \0           | Null character |
+Anchors:
+^ Symbol       ^ Description ^
+| \G           | Start of match |
+| <nowiki>^</nowiki>            | Start of string |
+| \A           | Start of string |
+| $            | End of string |
+| \Z           | End of string |
+| \z           | Absolute end of string |
+| \b           | Any word boundary character |
+| \B           | Any non-word boundary |
+| \w           | Any word character (letter, number, underscore) |
+| \W           | Any non-word character |
+Flags/Modifiers (eg: "/regex here.../g"):
+^ Symbol       ^ Description  ^
+| g  | Global (do not return after first match) |
+| i  | Case insensitive |
+| m  | Multiline (dot matches newlines, <nowiki>^</nowiki> and $ match start/end of line)  |
+| s  | Single line (dot matches newline) |
+| u  | Unicode (match with full unicode) |
+| x  | eXtended (ignore whitespace) |
+| X  | eXtra (disallow meaningless excapes|
+| o  | Perform #{...} substitutions only once |
+| A  | Anchored (anchor to start of pattern) |
+| J  | Duplicate group names (allow duplicate subpattern names) |
+| D  | Dollar end only ($ matches only end of pattern) |
+== Using Regex in PHP ==
+Can be used as ''ereg()'' or ''preg_match()''.  Here is a comparison:
+<code php>
+<?php
+if(ereg('[^0-9A-Za-z]',$test_string)) // will be true if characters arnt 0-9, A-Z or a-z.
+if(preg_match('/[^0-9A-Za-z]/',$test_string)) // this is the preg_match version. the /'s are now required.
+?>
+</code>
+Using options:
+<code php>
+<?php
+// The "i" after the pattern delimiter indicates a case-insensitive search
+if (preg_match("/php/i", "PHP is the web scripting language of choice.")) {
+    echo "A match was found.";
+} else {
+    echo "A match was not found.";
+}
+?>
+</code>
+Example using ''preg_replace()'':
+<code php>
+// Strip ending commas
+$str = preg_replace('/,$/s', '', $str);
+// Strip leading/trailing commas with whitespace around
+$str = preg_replace('/^[,\s]+|[\s,]+$/', '', $str);
+</code>
+== References ==
+  * [[http://www.rexegg.com/regex-quickstart.html|Regex Cheat Sheet]]
+  * [[https://regex101.com|Regex 101]]