How to code this regular expression ...

I'm coding in PHP, but this is a generic regular expression question.

I'm trying to interrogate a character string of any length, to see if it contains the letter c followed by a number of up to 3 digits and a period (.) but at the same time rejecting other more complex strings. So ..

You are a clown99. - false
You are a clown c99. - true
You will love c3po. - false
You will love c3.po - true

Is there a regular expression syntax to check for this ?

 

$testCases = array("You are a clown99.", "You are a clown c99.","You will love c3po.","You will love c3.po");
$pattern = '/c(\d){1,3}\./';

foreach ($testCases as $case) {
	if(preg_match($pattern, $case) == TRUE) {
		print "Match on string: $case <br />";
	}
}

Code (markup):

explanation:
c // matches the c character
(\d){1,3} // matches a digit (/d) that appears 1 to 3 times {1,3}
\. // matches the period

If you wanted to match an upper or lower case C, use

$pattern = '/[C|c](\d){1,3}\./';

Code (markup):

 

Thanks for that

I found this site after I posted: http://www.regular-expressions.info/javascriptexample.html

and came up with this: [c][0-9]{1,3}\.

but yours looks a lot better

 

Your code is identical to mine in functionality.

The \d I used performs the same search as [0-9], and putting the c inside square brackets is fine as well.

Regular expressions are very useful, check out this website if you're looking for a good resource.

http://krijnhoetmer.nl/stuff/regex/cheat-sheet/

Also, that javascript regex tester is a very nice find.