Php – Warning: preg_match() [function.preg-match]: Compilation failed: nothing to repeat at offset

PHPpreg-matchregex

i'm trying to change the preg_match check from url checking to username checking which is min/max 2-16chrs, dash, space & hypen acceptable. i'm getting this error

Warning: preg_match() [function.preg-match]: Compilation failed: nothing to repeat at offset 14

if(empty($string) || preg_match("#^([\w- ]{2,16}*(?:.[\w- ]{2,16}*)+):?(d+)?/?#i", $string))

old code that looked for URL

if(empty($string) || preg_match("#^(http|https|ftp)://([A-Z0-9][A-Z0-9_-]*(?:.[A-Z0-9][A-Z0-9_-]*)+):?(d+)?/?#i", $string))

Best Answer

The problem is here:

[\w- ]{2,16}*

You can't use {2,16} and * together, you can only use one or the other.

If you were looking to match groups of 2 to 16 [\w- ]s, at least 0 times, wrap it in a subpattern and attach the * outside:

(?:[\w- ]{2,16})*

Related Solutions

Php – the regex pattern for datetime (2008-09-01 12:35:45 )

@Espo: I just have to say that regex is incredible. I'd hate to have to write the code that did something useful with the matches, such as if you wanted to actually find out what date and time the user typed.

It seems like Tom's solution would be more tenable, as it is about a zillion times simpler and with the addition of some parentheses you can easily get at the values the user typed:

(\d{4})-(\d{2})-(\d{2}) (\d{2}):(\d{2}):(\d{2})

If you're using perl, then you can get the values out with something like this:

$year = $1;
$month = $2;
$day = $3;
$hour = $4;
$minute = $5;
$second = $6;

Other languages will have a similar capability. Note that you will need to make some minor mods to the regex if you want to accept values such as single-digit months.

Php – preg_match: nothing to repeat / no match

+ is a special character that indicates 1 or more of the previous character, and by not escaping it you are applying it to the caret. escape it with \ and it will match a literal plus sign.

if(!preg_match('/^\+[0-9]$/', '+1234567'))

EDIT:

The reason why it didn't match is because you specified 1 digit from 0-9 and the end of the string with $. You need to make it a variable amount of digits.

if(!preg_match('/^\+[0-9]+$/', '+1234567')) {

Shorter version:

if(!preg_match('/^\+\d+$/', '+1234567')) {

Best Answer

Related Solutions

Php – the regex pattern for datetime (2008-09-01 12:35:45 )

Php – preg_match: nothing to repeat / no match

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