Regular Expressions

[dcotter]

I'm coding a site that has a registration page, in which users need to choose a username and password. These fields can only contain the following characters:

A-Z,a-z,0-9, and "_"

Any other characters in these fields, including the " " (space character), single or double quotes, or any other invalid character needs to return an error.

On my registration page, I have the following setup:

function check_chars($string) {
if (valid) {
return true;
} else {
return false;
}
}

// code
if (!$check_chars($username)) {
// error handling
}
if (!$check_chars($password)) {
// error handling
}

I just need the check_chars function. Can someone provide a reliable function to do this, or point me in the right direction? I'd rather not spend hours coding and testing this function if someone else has already written something =)

TIA,

Daren Cotter

[kparker]

You can say

if (eregi("^{[a-z0-9_]+$",} $name))
   // it's valid

[dcotter]

I don't see anything about A-Z...am I correct in saying this would be exactly what I need:

if (eregi("^{[A-Za-z0-9_]+$",} $name))
// it's valid

?? Any character other than the 63 would produce an error?

[mp96brbj]

By calling eregi() instead of ereg(), the matching is done in a case-insensitive manner, so [a-z] matches both [a-z] and [A-Z].