How to check if an integer is within a range?

Question

Is there a way to test a range without doing this redundant code:

if ($int>$min && $int<$max)

?

Like a function:

Answer 1

I'm not able to comment (not enough reputation) so I'll amend Luis Rosety's answer here:

function between($n, $a, $b) {
    return ($n-$a)*($n-$b) <= 0;
}

This function works also in cases where n == a or n == b.

Proof: Let n belong to range [a,b], where [a,b] is a subset of real numbers.

Now a <= n <= b. Then n-a >= 0 and n-b <= 0. That means that (n-a)*(n-b) <= 0.

Case b <= n <= a works similarly.