Regular expressions: Difference between revisions

Latest revision as of 21:06, 13 September 2014

In SMF2.0, regular expressions (regex) can be used in input masks as found in the Advanced Settings when creating or editing a custom profile field.

Using Regular Expressions

When entering regular expressions (regex), you must surround them with delimiters such as tildes (~) or double quotes ("), otherwise they will not work and there will be no warning of this failure. Two examples of the correct way of entering regular expressions for SMF are: ~[12][0-9]{3}~ or "[12][0-9]{3}"

Examples

The following examples give an idea of what can be done with regular expressions:

"[A-Za-z]+" - Match all upper and lower case alphabet characters.
"[0-9]+" - Match all numeric characters.
"[A-Za-z0-9]{7}" - Match all upper and lower case alphabet and numeric characters seven times.
"[^0-9]?" - Forbid any number from being matched.
"^([A-Fa-f0-9]{3}|[A-Fa-f0-9]{6})$" - Only allow 3 or 6 character hexcodes.

Meta-characters

In regular expressions you can use meta-characters to define the search for matches.

? - None or one match of the preceding expression.
+ - One or more matches of the preceding expression.
* - None or more matches of the preceding expression.
{n} - Matches the preceding expression exactly n times.
{n,} - Matches the preceding expression at least n times.
{,n} - Matches the preceding expression no more than n times.
{n,m} - Matches the preceding expression at least n times, but no more than m times.
^ - When used outside square brackets, it marks the start of the string. When used inside square brackets it has the affect of negating the class, but only if it is the first character.
$ - The end of the string.
\ - Escapes the next character.

@@ Line 1: / Line 1: @@
-Regular expressions can be used in the advanced profile fields/custom profile fields.
+In SMF2.0, regular expressions (regex) can be used in input masks as found in the ''[[SMF2.0:Features_and_Options#Advanced_Settings|Advanced Settings]]'' when creating or editing a custom profile field.
-The input mask is important for your forum's security. Validating the input from a user can help ensure that data is not used in a way you do not expect. We have provided some simple regular expressions as hints.
+==Using Regular Expressions==
-"[A-Za-z]+" - Match all upper and lower case alphabet characters.
+When entering regular expressions (regex), you must surround them with delimiters such as tildes (~) or double quotes ("), otherwise they will not work and there will be no warning of this failure. Two examples of the correct way of entering regular expressions for SMF are: '''<span style="color:#FF0000">~</span>'''[12][0-9]{3}'''<span style="color:#FF0000">~</span>''' or '''<span style="color:#FF0000">"</span>'''[12][0-9]{3}'''<span style="color:#FF0000">"</span>'''
-"[0-9]+" - Match all numeric characters.
-"[A-Za-z0-9]{7}" - Match all upper and lower case alphabet and numeric characters seven times.
-"[^0-9]?" - Forbid any number from being matched.
-"^([A-Fa-f0-9]{3}|[A-Fa-f0-9]{6})$" - Only allow 3 or 6 character hexcodes.
+===Examples===
-Additionally, special metacharacters ?+*^$ and {xx} can be defined.
+The following examples give an idea of what can be done with regular expressions:
-? - None or one match of previous expression.
-+ - One or more of previous expression.
-* - None or more of previous expression.
-{xx} - An exact number from previous expression.
-{xx,} - An exact number or more from previous expression.
-{,xx} - An exact number or less from previous expression.
-{xx,yy} - An exact match between the two numbers from previous expression.
-^ - Start of string.
-$ - End of string.
-\ - Escapes the next character.
+*'''<code>"[A-Za-z]+"</code>''' - Match all upper and lower case alphabet characters.
+*'''<code>"[0-9]+"</code>''' - Match all numeric characters.
+*'''<code>"[A-Za-z0-9]{7}"</code>''' - Match all upper and lower case alphabet and numeric characters seven times.
+*'''<code>"[^0-9]?"</code>''' - Forbid any number from being matched.
+*'''<code>"^([A-Fa-f0-9]{3}|[A-Fa-f0-9]{6})$" </code>''' - Only allow 3 or 6 character hexcodes.
-More information and advanced techniques may be found on the internet.
+===Meta-characters===
+In regular expressions you can use meta-characters to define the search for matches.
+*'''?''' - <u>None or one</u> match of the preceding expression.
+*'''+''' - <u>One or more</u> matches of the preceding expression.
+*'''<nowiki>*</nowiki>''' - <u>None or more</u> matches of the preceding expression.
+*'''{''n''}''' - Matches the preceding expression <u>exactly</u> ''n'' times.
+*'''{''n'',}''' - Matches the preceding expression <u>at least</u> ''n'' times.
+*'''{,''n''}''' - Matches the preceding expression <u>no more than</u> ''n'' times.
+*'''{''n'',''m''}''' - Matches the preceding expression <u>at least</u> ''n'' times, but <u>no more than</u> ''m'' times.
+*'''^''' - When used <u>outside</u> square brackets, it marks the start of the string. When used <u>inside</u> square brackets it has the affect of negating the class, but only if it is the first character.
+*'''$''' - The end of the string.
+*'''\''' - Escapes the next character.
+[[Category: As an administrator]]

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