Warning: preg_replace() [function.preg-replace]: Compilation failed: nothing to repeat at offset 1

Question

Can someone help debug this error?

Warning: preg_replace() [function.preg-replace]: Compilation failed: nothing to repeat at offset 1

Answer 1

* in regex means to match the previous character 0 or more times, while ( starts a capturing group. So, the * has nothing to repeat, since what comes before the * is a (, which cannot be repeated by itself, hence this warning.

To fix it, just escape the *, like so:

$uid = preg_replace("#(\*UTF8)[^A-Za-z0-9]#", "", $tmp);