Question

How can I create a regular expression which test if a number is divisible by i (2<=i<=10), 8 expressions in total? One can only assume that integers are positive. You can use symbols [] and [^] , ?, * and + , | and (). PHP’s ereg-function should accept it.

Answer 1

Unless this is a homework problem there is no reason to use regular expressions in this case.

Use the modulus operator, it gives you the remainder of the value divided by.

if($number%$i) { "This runs if $number modulus is not 0 (not evenly divisible by $i)" }
else { "This runs if $number modulus is 0 ( evenly Divisible by $i)" }

Edit: Oh it’s an interview question. Yes, the correct answer here is “That is not the correct tool for this problem!”