Regular expressions.

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I honestly thought I knew this stuff, but then I come to revise I find I actualy was clueless. There is some example code to illustrate.

Its Perl BTW.

Code:

$myString = "adcd";

if ($myString =~ m/\w{1,3}/){

   print("your pattern matches $myString");
} 

Now here's what I thought I knew. The characters {1,3} will match the string as long as the string contains 1 letter and NO MORE THAN 3 letters. Im obviously wrong because the code above actualy matches.

Can somone tell me what im doing wrong please.
Cheers.
Stu.

 

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It is matching on the first 3 characters. Put '$' at the end of the match string to stop it matching longer strings.

Edit: <cough> and of course a '^' at the start, otherwise it will match the last 3 characters!

Harry.

 

I'm paying too much attention to my course manual again. It is worded VERY badly, here is what it says regarding {1,4}

"must match at least once but no more than four times".

I take this to mean that if you have a string of five letters, then the match will fail. God I wish I'd self studied. In fact, with the manual being wrong about 90% of the time, I more or less HAVE.

Cheers Harry

 

Actualy - it is right - but it depends on how you read it!

Because matching is 'greedy' it will start by attempting to match 4 times. If you have a string with more than 4 characters in it it will match - it has found 4 characters. It doesn't care that there are more characters afterwards.

Harry.