Question

我正在尝试创建一个简单的程序，计算3种活动，骑自行车，慢跑和游泳所消耗的卡路里和磅数。我一直得到一个错误未定义的变量：calcPounds。

我在函数内部有变量，但它仍然告诉我它未定义。我本周刚刚开始使用PHP，所以我有点困惑。

谢谢！

PHP

function pounds_burned($calc){

    $biking = 200;
    $jogging = 475;
    $swimming = 275;
    $calories;
    $pounds = 3500;
    $calcPounds;       // **** ASSIGNMENT MISSING HERE ****

    $hoursBiking = floatval($_GET["bike"]);
    $hoursJogging = floatval($_GET["jog"]);
    $hoursSwimming = floatval($_GET["swim"]);

    if (!is_numeric($hoursBiking) or !is_numeric($hoursJogging) or !is_numeric($hoursSwimming)) {
        echo 'Enter numeric values only' . "<br />";
    }

    if (empty($hoursBiking) or empty($hoursJogging) or empty($hoursSwimming)) {
        echo "All fields are required to be valid numbers!!";
        echo "<p><a href=\"calories.html\">Try again?</a></p>\n";
    }
    else {  
        $calcPounds = round(($biking * $hoursBiking) + 
            ($jogging * $hoursJogging) + ($swimming * $hourssSwimming));
    }
  }
    echo "Number of pounds worked off is " . round($calcPounds);

    $calories = $calcPounds / $pounds;
    echo "Number of calories burned is " .round($calories);
  ?>

HTML

<form action="calorie_calc.php" method="GET" onsubmit="return validateForm()">

  <table border="0">
  <tr>
    <td>Enter number of hours bicycling</td>
    <td><input type="text" name="bike" id="bike" size = "10" /></td>
  </tr>  
  <tr>
    <td>Enter number of hours jogging</td>
    <td><input type="text" name="jog" id="jog" size = "10" /></td>
  </tr>     
  <tr>
   <tr>
     <td>Enter number of hours swimming</td>
     <td><input type="text" name="swim" id="swim" size = "10" /></td>
  </tr>
    <td><input type="submit" name="calc" id="calc" value="Compute Pounds" /></td>
    <td><input type="reset" name="resetButton" id="resetButton" value="Reset" /></td>
  </tr>             
  </table>

  </form>

Answer 1

在您的档案calorie_calc.php

中

<?php

if (isset($_GET["calc"])){
    $biking = 200;
    $jogging = 475;
    $swimming = 275;
    $calories = 0;
    $pounds = 3500;
    $calcPounds = 0;

    $hoursBiking = floatval($_GET["bike"]);
    $hoursJogging = floatval($_GET["jog"]);
    $hoursSwimming = floatval($_GET["swim"]);

    if (!is_numeric($hoursBiking) or !is_numeric($hoursJogging) or !is_numeric($hoursSwimming)) {
        echo 'Enter numeric values only' . "<br />";
    }

    if (empty($hoursBiking) or empty($hoursJogging) or empty($hoursSwimming)) {
        echo "All fields are required to be valid numbers!!";
        echo "<p><a href=\"calories.html\">Try again?</a></p>\n";
    }
    else {  
        $calcPounds = round(($biking * $hoursBiking) + 
            ($jogging * $hoursJogging) + ($swimming * $hourssSwimming));
    }
    echo "Number of pounds worked off is " . round($calcPounds);

    $calories = $calcPounds / $pounds;
    echo "Number of calories burned is " .round($calories);
}
?>

Answer 2

您的变量$calcpounds确实位于函数内部，但这不是它的使用位置。您的代码将始终执行以下行：

echo "Number of pounds worked off is " . round($calcPounds);
$calories = $calcPounds / $pounds;
echo "Number of calories burned is " .round($calories);

在函数之外，因此$calcpounds未初始化。

$calcpounds也不保证在你的函数内初始化，但即使它是，它也不会在外面可见。

您需要return该函数中的值才能在以后使用该值，但在此您甚至不会调用pounds_burned()让它返回值。

我建议您重新构建代码：

从函数中删除验证：将其作为主程序流程的一部分执行
将三个变量（$ hoursJogging等）作为参数传递给函数。
让函数执行算术，并返回结果
存储结果并根据需要输出消息。

Answer 3

如果您处于生产模式，最好不要显示E_ALL之类的错误，这是Notice错误，当然如果您正试图摆脱此问题

if (empty($hoursBiking) or empty($hoursJogging) or empty($hoursSwimming)) {
  $calcPounds = null; // Add this line for a quick fix, otherwise refactor whole code
  echo "All fields are required to be valid numbers!!";
  echo "<p><a href=\"calories.html\">Try again?</a></p>\n";
}

未定义的变量错误

3 个答案: