Password verify

[Anon]

Hi!
I want to verify if the user submit password got any special characters, I only allow they submit [a-zA-Z0-9],so I use:

if (!ereg("[a-zA-Z0-9]",$password)){
echo "Your paswd got something we don't like";
}

But I found it seems return true even I enter something like:"@!#$" in my password value, why ?
Didn't it should only allow alpha and numberic ?

[Anon]

Try this... ^ means NOT if I remember right. So it's looking for something that is not alphanumeric.

if (ereg("[^{a-zA-Z0-9]",$password)){}
echo "Your paswd got something we don't like";
}

---John Holmes...

[Anon]

Still needs a little refinement. The problem with both eregs here is that they aren't forced to match the entire string, but instead are content to match a single character anywhere within it.

Instead, use ^ and $ to anchor the pattern to the beginning and end of the string, and use + (non-empty closure) after the character class:

if (! ereg('^{[a-zA-Z0-9]+$',$password))}
   echo "bad password";

You can also use {} notation to specify specific length requirements, e.g. password must be between 6 and 20 chars:

if (! ereg('^{[a-zA-Z0-9]{6,20}$',$password))}

This is quick and convenient; however it does have the disadvantage that it lumps all the possible failures together, so you can't issue separate informative messages such as 'letters and digits only', 'too short', etc.

[Anon]

Hi!
Thanks for your help, it works, but I still got some confuse about why using "+" ?

James

Instead, use ^ and $ to anchor the pattern to the beginning and end of the string, and use + (non-empty closure) after the character class:

if (! ereg('^{[a-zA-Z0-9]+$',$password))}
   echo "bad password";

You can also use {} notation to specify specific length requirements, e.g. password must be between 6 and 20 chars:

if (! ereg('^{[a-zA-Z0-9]{6,20}$',$password))}

This is quick and convenient; however it does have the disadvantage that it lumps all the possible failures together, so you can't issue separate informative messages such as 'letters and digits only', 'too short', etc.

[Anon]

• means "one or more" so you make sure the password isn't empty.

---JH