Regular expression examples

The following examples show some regular expressions and describe what they match:

Expression	Description
[\?&]value=	A URL parameter value in a URL.
[A-Z]:(\\[A-Z0-9_]+)+	An uppercase DOS/Windows path in which (a) is not the root of a drive, and (b) has only letters, numbers, and underscores in its text.
[A-Za-z][A-Za-z0-9_]*	A ColdFusion variable with no qualifier.
([A-Za-z][A-Za-z0-9_])(\.[A-Za-z] [A-Za-z0-9_])?	A ColdFusion variable with no more than one qualifier; for example, Form.VarName, but not Form.Image.VarName.
(\+\|-)?[1-9][0-9]*	An integer that does not begin with a zero and has an optional sign.
(\+\|-)?[1-9][0-9](\.[0-9])?	A real number.
(\+\|-)?[1-9]\.[0-9]*E(\+\|-)?[0-9]+	A real number in engineering notation.
a{2,4}	Two to four occurrences of "a": aa, aaa, aaaa.
(ba){3,}	At least three "ba" pairs: bababa, babababa, and so on.

Comments are no longer accepted for ColdFusion MX 6.1. ColdFusion 8 is the current version.

Comments

RBCH said on Nov 12, 2003 at 9:36 PM :

[A-Za-z][A-Za-z0-9_]* = A ColdFusion variable with no qualifier.

This is incorrect as it only matches the first character (using REFind).

The correct expression is:

^[A-Za-z][A-Za-z0-9]*$

No screen name said on May 3, 2004 at 2:51 AM :

Should not the regular expression for 'real' values be something like:

(\+|-)?[0-9]+(\.[0-9]*)?

Otherwise, values like '0.12' will not be found, I guess.

ASandstrom said on May 3, 2004 at 8:22 AM :

You are correct. The documented regular expression finds 0.12, for example, but at the wrong location in the string.
You can test it with the following:
<cfset regexpressionMM="(\+|-)?[1-9][0-9]*(\.[0-9]*)?">
<cfset regexpressionALT="(\+|-)?[0-9]+(\.[0-9]*)?">

<cfset stringtosearch="It finds 0.12 at position ten.">

<cfset resultoffindMM=REFind(regexpressionMM, stringtosearch)>
<cfset resultoffindALT=REFind(regexpressionALT, stringtosearch)>

<cfoutput>
The real number starts at position 10.<br>
The result is of the documented regular expression is #resultoffindMM#.<br>
The result of the proposed regular expressin is #resultoffindALT#.<br>
</cfoutput>

Thanks for the feedback!

switchbox said on Aug 7, 2004 at 7:30 PM :

[\?&]value=

Should say [\?&]attribute=

URL parameters are attribute=value pairs.

halL said on Aug 10, 2004 at 11:12 AM :

With respect to the post by switchbox:
We should either delete the example or change it substantially.
The example only matches a URL parameter name, er, named, "value" and does not include the parameter value.

markus einfinger said on Oct 6, 2004 at 1:32 AM :

hi,

I'd like to use a pattern to check a text field for a correct url.

I found this one, but the browser complains that a ")" is missing. Any ideas how to fix this?

^(http://)([a-zA-Z0-9_\-]+)([\.][a-zA-Z0-9_\-]+)+([/][a-zA-Z0-9\~_\-]*)+([\.][a-zA-Z0-9_\-]+)*$

thanks,
markus

Glizman said on Jan 9, 2006 at 7:51 AM :

In response to 'No screen name' and ASandstrom on real numbers, the modified answer:

(\+|-)?[0-9]+(\.[0-9]*)?

would highlight

10.

as correct. Here's a minor modifcation to require a digit to the right of the decimal point if one is present:

(\+|-)?[0-9]+(\.[0-9]+)?


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