check my regex?

[haku]

Regex is my weak point. I'm not so good at it. I just put this one together - can someone give it a lookover? It's supposed to match this pattern:

* string starts with at least one digit, but could be multiple digits. No letters, only numbers

* after the initial digits will be the string '_sign_in'

* there will never be anything else - nothing between the digits and _sign_in, and _sign_in will always be the end of the string

 

Here is what I have come up with:

 

/^[0-9]+(_sign_in)$/

 

I think it's probably ok, but as I say, I'm not the best with regex. Can someone let me know if I've missed anything, or if it's ok? Thanks.

[Adam]

Looks good to me, except unless you wish to capture the text "_sign_in" you don't need the brackets:

 

/^[0-9]+_sign_in$/

[thebadbad]

And just so you know, the dollar also matches immediately before the final character if it is a newline, unless you set the D modifier. So without setting it, a string like

 

$str = "1_sign_in\n";

or

 

$str = '1_sign_in
'; //only on Linux/Unix

would be matched by your pattern.

[haku]

Thanks guys - a couple of questions:

 

Mr. Adam - what do you mean 'capture the text'? As in return it to the calling function?

thebadbad - two questions. First, by 'set the D modifier', do you mean '/regex here/D'? Next, I'm checking a value pulled from the database that will never have a new line after it. I should be ok right?

 

Thanks guys.

[thebadbad]

A set of parentheses captures the match, as in stores it in the variable provided as the optional third parameter to preg_match() (often called $matches).

 

And to your second question; yep, /pattern/D is right. If you're certain about the data (or if it doesn't matter) it's not necessary to use the D modifier, but I just tend to do it, when I want the dollar to match only at the very end of the string.

[haku]

Thanks - that clears it up for me.

 

I actually bought a book on regex a couple of months ago, as I know it's something I need to brush up on, but I've just been too busy to work on it.