php regex for min and max number length - php

Question

if(strlen(trim($steamid)) != 0)
{
$regex = "/^STEAM_0:(0|1):[0-9]{1}[0-9]{0,8}$/";
if(!ereg($regex, $ssteamid)){
echo "STEAM ID invalida";
}
}
My problem is that this isn't working as it should.
STEAM ID's have maximum of 18 characters and minimum of 17.
they always start with: STEAM_0:
Two true examples would be: STEAM_0:0:11111111 ; STEAM_0:1:1111111
And another thing is that after STEAM_0: always come an 0 or an 1 like demonstrated in the examples.

Answer 1

This:
$regex = "/^STEAM_0:(0|1):[0-9]{1}[0-9]{0,8}$/";
could be writter shorter as:
$regex = "/^STEAM_0:[01]:[0-9]{1,9}$/";
Since your ID is 17 or 18 chars long, adjust the regex to it:
$regex = "/^STEAM_0:[01]:[0-9]{7,8}$/";
Finally, note that ereg is deprecated as of PHP 5.3. This snippet shows your php/regex with preg_match:
<?php
$steamid = "STEAM_0:0:11111111";
if(strlen(trim($steamid)) != 0)
{
$regex = "/^STEAM_0:[01]:[0-9]{7,8}$/";
if(!preg_match($regex, $steamid))
{
echo "STEAM ID invalida.\n";
} else {
echo "STEAM ID valida.\n";
}
}
?>

Answer 2

If the minimum length is 17 and the max length is 18, then you guys are looking at this at the wrong way.
This should do the job for you:
$regex = "/^STEAM_0:(0|1):[0-9]{7}[0-9]?$/";
And also, when in doubt, test your regexp with some of the online regexp tools like http://www.regexplanet.com/simple/index.html

Answer 3

Try this:
$regex = "/^STEAM_0:(0|1):[0-9]{8,9}$/";
It matches:
STEAM_0: at the beginning, followed
by
a 0 or a 1, followed by a :,
followed by
Either 8 or 9 digits, making the
total number of characters 17 or 18

Answer 4

You should be avoiding use of ereg() and its related functions; they've deprecated for quite a long time in PHP. Use thepreg_xx() functions instead (preg_match() in this case).
One of the differences between preg_match() and ereg() is that ereg() does not expect you to include the slash characters to start and end the regex, whereas preg_match() does. This is probably the main reason your code isn't working: since you've included the slashes, your use of ereg() won't work, but is you switch to preg_match(), the same expression should work fine.
So a simple change to preg_match() should sort you problem. But while I'm here, I may also suggest that you can shorten your regex string quite considerably. Try something like this:
$regex = "/^STEAM_0:[01]:[0-9]{8,9}$/";
if(!preg_match($regex, $ssteamid)) {
echo "STEAM ID invalid";
}
Hope that helps.