ereg eregi help

[chings]

i want to validate the username , only alphabet and number is allowed and the length is between 6-20

so

eregi("[a-z0-9]{6,20}",$username)

but it dosen't work , always go true,

pls help

[laserlight]

You could consider doing it without regex:

$len = strlen($username);
if ($len > 5 && $len < 21 && ctype_alnum($username)) {
	// username is valid
} else {
	// username is invalid
}

But if you insist, what you were missing are the assertions for the start and end of subject:

if (preg_match('/^[a-z0-1]{6,20}$/i', $username)) {
	// username is valid
} else {
	// username is invalid
}

[chings]

thanks a lot

but what why /^ and $/i is needed .

[Weedpacket]

Those are the "the assertions for the start and end of subject" laserlight mentioned, along with the expression delimiters [man]preg_match[/man] requires, and an 'i' to make the matching case-insensitive.