Esercizio

<?php
    $value = str_split(strtolower($_GET["input"]), 1);
    $i = 0;
    $j = 0;
    $fr = [];
    foreach($value as $char){
        if(($char >= 'a' && $char <= 'z')) {
            $i += 1;
        } elseif($char >= '0' || $char <= '9'){
            $j += 1;
        }

        if(array_key_exists($char, $fr)) {
            $v = explode('.', $fr[$char])[1] + 1;
            $fr[$char] = "$char.$v";
        } else {
            $fr[$char] = "$char.1";
        }
    }

    echo "Sono presenti $i vocali e consonanti\n";
    echo "Sono presenti $j caratteri numerici\n";
    foreach($fr as $elem)
    {
        $v = explode(".", $elem)[1] / count($fr) * 100;
        $l = explode(".", $elem)[0];
        echo "Il carattere $l ha frequenza $v%\n";
    }
?>