Question

Sorry if the title is confusing.

I have several string expressions in an array like these:

var1 <= 6  && var1 > 3
var1 > 2  
var1 > 4.5

var2 < 22.5  
var2 >= 14.25  
var2 < 16

How can I go about evaluating all of the expressions to determine:

var1 min
var1 max
var2 min
var2 max

I understand that with the expressions that are not “or equal to” I won’t be able to get an exact value. That is alright.

Answer 1

<?php

    $arr = array("var1 <= 6",
    "var1 > 2",
    "var1 > 4.5",

    "var2 < 22.5",
    "var2 >= 14.25", 
    "var2 < 16");

    function find_min_max($arr, $variable) {
        $min = '-inf';
        $max = 'inf';
        while (list($i, $v) = each($arr)) {
            list($var, $rel, $value) = preg_split('/\s+/', $v);
            if ($var != $variable) continue;
            if ($rel == "<" || $rel == "<=") {
                if ($value < $max)
                    $max = $value;
            }
            else if ($rel == ">" || $rel == ">=") {
                if ($value > $min)
                    $min = $value;
            }
        }
        return array($min, $max);
    }
    list($min, $max) = find_min_max($arr, "var1");
    echo "var1 $min - $max \n";
    list($min, $max) = find_min_max($arr, "var2");
    echo "var3 $min - $max \n";
?>