PHP平均计算器不能正确显示结果

Question

我创建一个PHP计算器，需要使用以下类，然后打印出用户的名字和他们取得的平均分数。这是我到目前为止的代码，但是它没有正确显示，它说有丢失的参数和未定义的变量，但是我不确定我哪里出错了！

<?php 

class person {

public $name;

}
class student extends person {

function student ($name, $grade1, $grade2) {
    if(is_numeric($grade1) && is_numeric($grade2)){
        $grades = array($grade1, $grade2);
    }
    elseif (is_numeric($grade1)) {
        $grade2 = 0;
    }
    else {
        $grade1 = 0;
    }
}

function average ($grades) {
     $length = count($grades);
     $total = 0;

  for ($i = 0; $i < $length; $i++) {
    $total = $total + $grades[i];
  }

  $average = $total / $length;
  return $average;

}
 }

$person1 = new student ($_POST['firstName'], $_POST['firstGrade1'],  $_POST['firstGrade2']);
$person2 = new student ($_POST['secondName'], $_POST['secondGrade1'], $_POST['secondGrade2']);
$person3 = new student ($_POST['thirdName'], $_POST['thirdGrade1'], $_POST['thirdGrade2']);

echo "<br/> $person1->name" . "achieved an average of" . "$person1->average();";
echo "<br/> $person2->name" . "achieved an average of" . "$person2->average();";
echo "<br/> $person3->name" . "achieved an average of" . "$person3->average();";

?>

错误消息：警告：在C:\Program Files（x86）\EasyHP-DevServer-14.1VC11\data\localweb\my portable Files\练习4\average中调用的student:：average（）缺少参数1。php位于第40行，在C:\Program Files（x86）\EasyHP-DevServer-14.1VC11\data\localweb\my portable Files\练习4\average中定义。php第22行

注意：未定义变量：C:\Program Files（x86）\EasyHP-DevServer-14.1VC11\data\localweb\my portable Files\练习4\average中的等级。php第23行

警告：在C：\Program Files（x86）\EasyPHP-DevServer-14.1VC11\data\localweb\我的便携式文件\练习4\第30行上的average.php中除以零

Answer 1

以下是增强类。您会注意到它们有构造函数和函数来请求变量。私有变量通常是首选方法，因为它们受到保护，因此不能在类外修改。

class person {
    private $name = "";

    public function __construct ($nameV) {
        $this->name = $nameV;
    }

    public function getName() {
        return $this->name;
    }
}

class student extends person {

    private $grades;

public function __construct ($name, $grade1, $grade2) {
    parent::__construct($name);

    if ( ! is_numeric($grade1)) { $grade1 = 0; }
    if ( ! is_numeric($grade2)) { $grade2 = 0; }
    $this->grades = array($grade1, $grade2);
}

    public function average () {
        $length = count($this->grades);
        $total = 0;

      for ($i = 0; $i < $length; $i++) {
        $total = $total + $this->grades[$i];
      }

      $average = $total / $length;
      return $average;
    }
 }

导出代码如下所示：

echo "<br/>" . $person1->getName() . " achieved an average of " . $person1->average();
echo "<br/>" . $person2->getName() . " achieved an average of " . $person2->average();
echo "<br/>" . $person3->getName() . " achieved an average of " . $person3->average();

由于没有表格，我使用以下数据进行了测试：

$person1 = new student ("XYZ", 1, 2);
$person2 = new student ("XYZ2", 100, 20);
$person3 = new student ("XYZ3", 95, 94);

其中出口：

XYZ achieved an average of 1.5
XYZ2 achieved an average of 60
XYZ3 achieved an average of 94.5

Answer 2

您似乎没有返回$等级变量。它可能没有定义，因为您没有返回任何东西。

您的方法：

function student ($name, $grade1, $grade2) {
    if(is_numeric($grade1) && is_numeric($grade2)){
        $grades = array($grade1, $grade2);
    }
    elseif (is_numeric($grade1)) {
        $grade2 = 0;
        $grades = array($grade1, $grade2);
    }
    else {
        $grade1 = 0;
        $grades = array($grade1, $grade2);
    }
    return $grades
}

需要看起来更像那样。您还需要实际将grade1和grad2添加到您返回的数组中的备用条件。