If you want a safe and flexible solution, this allows you to define a method which is executed depending on the operator matching the key in an array, it only works with two operands, but the last one in the examples #
just multiplies the first value by 4 and returns the value...
$operators = [ "<=" => function ($a, $b) { return $a <= $b;},
"<" => function ($a, $b) { return $a < $b;},
">=" => function ($a, $b) { return $a >= $b;},
">" => function ($a, $b) { return $a > $b;},
"#" => function ($a) { return $a * 4; }];
$t = 5;
$s = "<=";
$r = 6;
var_dump($operators[$s]($t,$r));
$s = "<";
var_dump($operators[$s]($t,$r));
$s = ">=";
var_dump($operators[$s]($t,$r));
$s = ">";
var_dump($operators[$s]($t,$r));
$s = "#";
var_dump($operators[$s]($t,$r));
gives...
/home/nigel/workspace2/Test/t1.php:14:
bool(true)
/home/nigel/workspace2/Test/t1.php:17:
bool(true)
/home/nigel/workspace2/Test/t1.php:20:
bool(false)
/home/nigel/workspace2/Test/t1.php:23:
bool(false)
/home/nigel/workspace2/Test/t1.php:26:
int(20)
It's a bit convoluted, but also extensible and safe.