0 in switch case?

Question

Hello!

Sorry for maybe dumb question, but i have HUGE problem with one case when i have some int variable with value of 0(zero).

            switch ($starost_vozila){
                case (0):
                    switch ($podaci['tip_motora']){
                        case ("motor1"):
                            $eko_taksa = 485;
                        break;
                        case ("motor2"):
                            $eko_taksa = 243;
                        break;
                        case ("motor3"):
                            $eko_taksa = 121;
                        break;
                        case ("motor4"):
                            $eko_taksa = 194;
                        break;
                    }
                break;
                case ($starost_vozila < 6):
                    switch ($podaci['tip_motora']){
                        case ("motor1"):
                            $eko_taksa = 485;
                        break;
                        case ("motor2"):
                            $eko_taksa = 243;
                        break;
                        case ("motor3"):
                            $eko_taksa = 121;
                        break;
                        case ("motor4"):
                            $eko_taksa = 194;
                        break;
                    }
                break;
                case ($starost_vozila > 5 && $starost_vozila < 11):
                    switch ($podaci['tip_motora']){
                        case ("motor1"):
                            $eko_taksa = 667;
                        break;
                        case ("motor2"):
                            $eko_taksa = 273;
                        break;
                        case ("motor3"):
                            $eko_taksa = 136;
                        break;
                        case ("motor4"):
                            $eko_taksa = 218;
                        break;
                    }
                break;

Switch continue more, but here is my problem, in this piece of code.

If i dont put "case (0):" and use this:

case ($starost_vozila >= 0 && $starost_vozila < 6):

Then the case that is next will somehow become active and it will print out that "$eko_taksa = 667;".

That is all problem when "$starost_vozila = 0" but when it is any number less then 6 than this case above works.

Every var here is int. Everything works ok except when "$starost_vozila = 0" and when i use "case ($starost_vozila >= 0 && $starost_vozila < 6):".

I have no idea what is going on... Oo

Sorry if this is dumb question. :(

Answer 1

using Switch is like == in "if statement" and not === (doesn't check for type). Only empty string or NULL would result in an Integer 0 - other than that, they are considered string 0.

Answer 2

You are using the switch incorrectly.

Your code is understood like this:

if ($starost_vozila == 0) {
    switch ($podaci['tip_motora']){
        case ("motor1"):
            $eko_taksa = 485;
        break;
        case ("motor2"):
            $eko_taksa = 243;
        break;
        case ("motor3"):
            $eko_taksa = 121;
        break;
        case ("motor4"):
            $eko_taksa = 194;
        break;
    }
} else if ($starost_vozila == ($starost_vozila < 6)) { //not what you want!!!
    switch ($podaci['tip_motora']){
        case ("motor1"):
            $eko_taksa = 485;
        break;
        case ("motor2"):
            $eko_taksa = 243;
        break;
        case ("motor3"):
            $eko_taksa = 121;
        break;
        case ("motor4"):
            $eko_taksa = 194;
        break;
    }
} else if ($starost_vozila == ($starost_vozila > 5 && $starost_vozila < 11)) { //not what you want!!!
    switch ($podaci['tip_motora']){
        case ("motor1"):
            $eko_taksa = 667;
        break;
        case ("motor2"):
            $eko_taksa = 273;
        break;
        case ("motor3"):
            $eko_taksa = 136;
        break;
        case ("motor4"):
            $eko_taksa = 218;
        break;
    }
}

For example, ($starost_vozila < 6) will become either TRUE or FALSE. $starost_vozila == ($starost_vozila < 6) is comparing $starost_vozila to either TRUE or FALSE, which is not what you want to do.

I suggest using if/elseif rather than switch in this case. For example:

if ($starost_vozila == 0) {
    ...
} else if ($starost_vozila < 6) {
    ...
} else if ($starost_vozila > 5 && $starost_vozila < 11) {
    ...
}

Answer 3

switch cases don't take statements that need to be evaluated. They take simple strings, booleans or numbers to be compared against

so say you have

$x = 0

switch( $x ) {
    case( $x < 10 ):
    ...
    break;
}

you are expecting that case to run but it doesn't and here's why

( $x < 10 ) evaluates to true so what you actually have is:

$x = 0

switch( $x ) {
    case true: //!!!
    ...
    break;
}

0 != true so the case fails

you need to use

if() {

} elseif() {

} else {

}