PHP笔记：设计简单的计算器

浅浅的花香味﹌ 2023-06-10 13:29 7阅读 0赞

<!doctype html>
    <head>
    <meta charset="utf-8">
    <title>简单的计数器</title>
    <?php
    if(isset($_POST['submit']))//isset检测变量是否设置,存在,或非NULL, 返回值为布尔, 如果变量存在返回true, 否则为false;
    { 
     $num1 = $_POST ['num1']; // 获取第一个输入框中的值,通过input中的name属性获得
     $select = $_POST ['select'];
     $num2 = $_POST ['num2'];
     if(is_numeric($num1)&&is_numeric($num2))// is_numeric()检测变量是否为数字或数字字符串,如10，'10'都返回true
     { 
      switch($select)
      { 
       case '+':
        $result=$num1+$num2;
        break;
       case '-':
        $result=$num1-$num2;
        break;
       case '*':
        $result=$num1*$num2;
        break;
       case '/':
        if($num2==0)//除数为零的情况
        { 
         echo "<script>alert('警告：除数为零，请重新输入！')</script>";
        }
        else
        { 
         $result=$num1/$num2;
         break;
        }
      }
      
     }
     else//当用户输入的不是数，可能是字符串则给用户提示
     { 
      echo "<script>alert('输入的不是一个数！')</script>";
      $num1 = $num2 = $result = ""; // 把表单里的内容清空
     }
    }
    else//如果不是提交页面，则把表单里的内容清空
    { 
        $num1 = $num2 = $result = "";
        $select = "+";
    }
    ?>
    <style>
    input,select{  width:6em; padding:8px 6px;}
    select{  color:red; font-weight:bold; }
    </style>
    </head>
    <body>
    <form method="post",action="">
     
     <input type="text" name="num1" value="<?php echo $num1 ?>">
     <select name="select">
      <option value="+" >+</option>
      <option value="-" >-</option>
      <option value="*" >*</option>
      <option value="/" >/</option>
     </select>
    <input type="text" name="num2" value="<?php echo $num2 ?>"> 
    <input type="submit" name="submit" value="=">
    <input type = "text" name="result" value="<?php echo $result?>">
    </form>
    </body>
    </html>

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