switch does not show the expected result

Question

What’s wrong? It was supposed to appear "no value", but when it starts with zero appears "very high value" in the message.

<?php
$num = 0;

switch ($num){
    case($num>100);
        echo'valor muito alto';
        break;
    case($num<80 && $num>51);
        echo'valor medio';
        break;
    case($num==50);
        echo'valor perfeito';
        break;
    case($num<=10);
        echo'valor muito baixo';
        break;
    case($num==0);
        echo'sem valor';
        break;
}
?>

Answer 1

The case does not work the way you expect. It is not a substitute for the if. See the documentation of him. The case accepts only one value, it only tests the equality of that value.

More or less what you want is this:

$num = 0;
if ($num > 100) echo 'valor muito alto';
else if ($num < 80 && $num > 51) echo 'valor medio';
else if ($num == 50) echo 'valor perfeito';
else if ($num <= 10) echo 'valor muito baixo';
else if ($num == 0) echo'sem valor';

Behold working in the ideone. And in the repl it.. Also put on the Github for future reference.

Still, there’s a logic error there. You can’t even understand what the goal is. It has bands of values overlapping, ranges of values that are not reached by any of the conditions.

Answer 2

I tested here and it worked, is a gambiarra, but meets your need, as I want to test more of a value in the case, I have to create a array, as @Maniero said, the case doesn’t work that way where you want, but you can do a gambiarra.

Creating 3 arrays with the range of values you want, and testing if the value exists within the array using the function in_array, looks nice...

<?php
    $num = 40;

    $array100_80 = array();
    $array79_51 = array();
    $array49_1 = array();

    for ($i = 80; $i <= 100; $i++) {
        $array100_80[$i] = $i;
    }

    for ($i = 51; $i <= 79; $i++) {
        $array79_51[$i] = $i;
    }

    for ($i = 1; $i <= 49; $i++) {
        $array49_1[$i] = $i;
    }

    switch ($num){
        case(0):
            echo'sem valor';
            break;
        case(in_array($num, $array100_80)):
            echo'valor muito alto';
            break;
        case(in_array($num, $array79_51)):
            echo'valor medio';
            break;
        case(50):
            echo'valor perfeito';
            break;
        case(in_array($num, $array49_1)):
            echo'valor muito baixo';
            break;
    }