Regex with three or more 7 and only small letters
<p>I need to write a Regex that matches string that:</p>

<p>-can't have letters k/l/m</p>

<p>-must have three or more digit 7</p>

<p>-can't have any big letters</p>

<p>-can't have a space sign</p>

<p>I wrote <code>"(?=.*7.*{3,})[^A-Zklm ]*"</code>, but I have some kind of feeling that this is not right, perhaphs I'm not seeing some obvious case where this is not gonna work, can anyone confirm?</p>