Regex validate alphanumeric string with slashes

May be I got up on the wrong side of the bed but
why this simple regex doesn’t work ?

if (preg_match("#^[0-9a-z\\/]+#i", "/user/1/***")) {
    echo "A match was found.";
} else {
    echo "A match was not found.";
// give A match was found.

Thanks in advance.

It works, copied it straight into shell and it finds the match so everything’s right there.

Thanks for the reply but
It shouldn’t match a string with special chars

You need to add “$” to the end.
Or do:

if ( preg_match( '~[^0-9A-Za-z\\/]~', $s ) )
  echo "Invalid! Must contain only 0-9 A-Z / ...";