<?php
    // Array of whole numbers
    $array = array(25, 23, 4, 56, 257);
    try {
        echo getMinValue($array);
    } catch(Exception $e) {
        echo $e->getMessage();
    }

    // Custom function that returns minimum value of an array
    function getMinValue($array) {
        if(empty($array)) {
            throw new Exception("No values in array");
        }
        $min = $array[0];
        foreach($array as $key => $val) {
            if($min > $val) {
                $min = $val;
            }
        }
        return $min;
    }
?>