如何在php中使用switch

if (isset($_POST["submit"])){
$oride='';
$count = "25";
$origin = $_POST["origin"];
$destinataion = $_POST["destination"];
$oride = ($destination = $_POST["destination"] - $origin= $_POST["origin"]);

    switch (true) {
    case ($count<="0"):
    echo "invalid";
        break;

    case ($count==="15"):
    echo $count;
        break;

    case ($count==="16"):
    $total = $count + "1";
    echo $total;
        break;
    default:
        echo "hello";
}  }

The code will compute 1st then execute switch depending on what is the result of the computation. I tried if else but it will be too long because the case will go up to 130.

You must use the var $count in switch statement and the constant in case this way

   switch ($count) {
    case  "0" :
    echo "invalid";
        break;

    case "15":
    echo $count;
        break;

    case "16":
    $total = $count + "1";
    echo $total;
        break;
    default:
        echo "hello";
        break;
  }

You have to provide an expression to the switch statement, while the case statements are just "versions" of the result of that expression. The only thing you can NOT do directly is the "<= 0" expression, but you can work around it:

if (isset($_POST["submit"])){
$oride='';
$count = "25";
$origin = $_POST["origin"];
$destinataion = $_POST["destination"];
$oride = ($destination = $_POST["destination"] - $origin= $_POST["origin"]);

// --- normalize $count:
$count = $count <= 0 ? 0 : $count;

// use $count as expression:
    switch ($count) {
    case 0:
    echo "invalid";
        break;

    case "15":
    echo $count;
        break;

    case "16":
    $total = $count + "1";
    echo $total;
        break;
    default:
        echo "hello";
}  }