[RESOLVED] Regular Expression, letters only

wmhop

I've been trying to create a regex that says a string must be letters only the combinations that I thought would work, don't:

preg_match("/[a-zA-Z]/", $string)

preg_match("/\w/", $string)

but it will match "string" or "string#" or "string@!" as long as there are letters in the string my regex will match it. But I only want it to match if there are only letters.

Thanks for any help you can offer.

wmhop

preg_match("/^{\b[a-zA-Z]+\b$/",} $string)

this seems to work as i need it but does anyone see any potential problems with this. I've had a hard time wrapping my mind around the way regular expressions work. If not I'll mark this resolved.

dalecosp

I believe you're mixing up your syntax here (but IANAE when it comes to regexps...)

"[a-zA-Z]" is POSIX compatible string, so you'd need to use [man]ereg/man to make it work. Maybe like this:

$exp="[a-zA-Z]";
$string="foo34foo";
if (ereg($exp,$string)) {
   // do something
}

Only problem, as you've already noticed: it matches any occurence of a "letter" ...

In the Perl-Compatible Syntax (used with preg_match and friends), the class "w" is roughly equivalent to [a-zA-Z0-9] in POSIX syntax, so once again, you can get a number to match.

Off the top of my head (without much study), I've this:

<?php

$exp="[!-@{-~]";

$string=array("f?jdksl","foo", "bar", "!3j3","1234");

foreach ($string as $s) {

   if (!ereg($exp,$s)) {
      echo "$s is true \n";
   } else {
      echo "$s is false! \n";
   }
}
?>

Dunno if it's much help, though... and, it still might let a stray char or two into your input. I'm quite braindead ATM (it's Saturday night...) ... mebbe someone lucid can come along and help before too much longer...

dalecosp

wmhop wrote:
preg_match("/^{\b[a-zA-Z]+\b$/",} $string)

this seems to work as i need it but does anyone see any potential problems with this. I've had a hard time wrapping my mind around the way regular expressions work. If not I'll mark this resolved.

Hrm, didn't see this when I posted. A few distractions, perhaps, or else time stood still for 21 minutes... :rolleyes: