用PHP进行简单货币换算的问题

Question

我无法获取要正确转换的所选货币的价值。 我是否正确设置了阵列？

<?php

    $amount_input = filter_input(INPUT_POST, 'amount_input');
    $currency1 = filter_input(INPUT_POST, 'currency_type_from');
    $currency2 = filter_input(INPUT_POST, 'currency_type_to');


    $currencies = array();

    $currencies['GBP'] = array(
        'GBP' => 1,
        'EUR' => 1.09710,
        'USD' => 1.28917
    );

   $currencies['EUR'] = array(
        'EUR' => 1,
        'GBP' => 0.911383,
        'USD' => 1.17616
    );

    $currencies['USB'] = array(
        'USD' => 1,
        'EUR' => 0.849851,
        'GBP' => 0.774699
    );

    $currencies = 0; // when I comment his I get an undefined index at the line below

    $amount_output = $amount_input*$currencies[$currency1][$currency2];

    ?>

表格将货币转换为选择类型

 <form action="converter.php" method="post">                
      <select name="currency_type_from" class="form-control">

          <option value="EUR">EUR</option>
          <option value="GBP">GBP</option>
          <option value="USD">USD</option>
      </select>

         <input name="amount_input" type="text"/>

      <select name="currency_type_to" class="form-control">

          <option value="EUR">EUR</option>
          <option value="GBP">GBP</option>
          <option value="USD">USD</option>
      </select>

     <input name="amount_output" type="text" value="<?php echo $amount_output; ?>" /> // value are not being input converted here?

      <input type="submit" name="submit" value="Convert"></input>

        </form> 

如果$ currencies = 0，也可能会得到未定义的索引错误； 是评论

Answer 1

做如下

1）如果要在同一页面上输出，则不要添加第二页的动作（形式）。 留空。

2）在Form之前添加php代码，以便获得融合价值

<?php
$amount_output = "";
$amount_input = "";
if($_POST)
{
  $amount_input = filter_input(INPUT_POST, 'amount_input');
    $currency1 = filter_input(INPUT_POST, 'currency_type_from');
    $currency2 = filter_input(INPUT_POST, 'currency_type_to');


    $currencies = array();

    $currencies['GBP'] = array(
        'GBP' => 1,
        'EUR' => 1.09710,
        'USD' => 1.28917
    );

   $currencies['EUR'] = array(
        'EUR' => 1,
        'GBP' => 0.911383,
        'USD' => 1.17616
    );

    $currencies['USB'] = array(
        'USD' => 1,
        'EUR' => 0.849851,
        'GBP' => 0.774699
    );

    $amount_output = $amount_input*$currencies[$currency1][$currency2];    
}
?>
<form action="" method="post">                
      <select name="currency_type_from" class="form-control">

          <option value="EUR">EUR</option>
          <option value="GBP">GBP</option>
          <option value="USD">USD</option>
      </select>

         <input name="amount_input" type="text" value="<?php echo $amount_input; ?>"/>

      <select name="currency_type_to" class="form-control">

          <option value="EUR">EUR</option>
          <option value="GBP">GBP</option>
          <option value="USD">USD</option>
      </select>

   <input name="amount_output" type="text" value="<?php echo $amount_output; ?>" />

      <input type="submit" name="submit" value="Convert"></input>

</form> 

Answer 2

将其添加到数组索引内的字符串中。 确保您的阵列密钥是USD或USB：

$amount_output = $amount_input*$currencies["$currency1"]["$currency2"];

对于测试代码，您可以在此处测试此完整的php代码：

    $amount_input = 4;
    $currency1 = 'GBP'; //from
    $currency2 = 'USD'; //to


    $currencies = array();

    $currencies['GBP'] = array(
        'GBP' => 1,
        'EUR' => 1.09710,
        'USD' => 1.28917
    );

   $currencies['EUR'] = array(
        'EUR' => 1,
        'GBP' => 0.911383,
        'USD' => 1.17616
    );

    $currencies['USD'] = array(
        'USD' => 1,
        'EUR' => 0.849851,
        'GBP' => 0.774699
    );

    //$currencies = 0; // when I comment his I get an undefined index at the line below

    $amount_output = $amount_input*$currencies["$currency1"]["$currency2"];
    echo '<pre>';
print_r($amount_output);

Answer 3

选择类型的默认选项如下所示：

currency_type_from  EUR
currency_type_to    EUR

但是数组键'EUR'在$currencies中不存在，因此会出现未定义的索引错误