Posted by Randell D. on 07/22/05 02:34

Folks,

I could do some basic regular expressions (which I picked up from sed,
in unix) but I'm afraid its been a while. I'm wondering if someone
could help out. I basically want to check that a string variable
contains only alphanumeric characters, in addition check for the
underscore. No decimal point check is required, and it should be a case
insensitive check.

I'm using PHP 4.x and would basically like to replace whatever is not
named above with an empty character (thus if a bang or question mark was
in a string, it would be removed from the string).

I know I could use something like preg_replace, but I don't know how to
say "when not found"... In sed, I could do something like

sed -e -i 's/[a-z]|[0-9]|_//g'

This would do the opposite of what I want to do (I think) but I'm lost
when it comes to PHP...

Can someone help me out, via the newsgroup (so all can learn?)

thanks in advance,
randell d.

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