从PHP的下拉菜单中输出关联数组

Question

So I am trying to get the year to be echo'd or printed in the output and then the population. 因此，我试图在输出中然后在人口中回显或打印年份。 So far. 至今。 I am able to have it print out the population when the option is selected... However, when I try to have a foreach command in, it prints out nothing. 选择选项时，我可以将其打印出来。但是，当我尝试输入foreach命令时，它什么也不会打印出来。 What am I am assuming its because it cannot get the year1 into the variable. 我在假设什么，因为它无法将year1放入变量中。 What am I doing wrong in my code? 我的代码在做什么错？

Here is my code: 这是我的代码：

 <?php

    if (($_SERVER['REQUEST_METHOD'] == 'POST') && isset($_POST['year1'])&& isset ($_POST['year2'])) 
        {
        $year1 = $_POST['year1'];
        $year2 = $_POST['year2'];

        }
function get_years($select)
 {
   $years=array('1790'=>'3929214','1800'=>5236631,'1810'=>7239881,
       '1820'=>9638453,'1830'=>12866020,'1840'=>17069453,
       '1850'=>23161876,'1860'=>31443321,'1870'=>38558371,
       '1880'=>49371340,'1890'=>62979766,'1900'=>76212168,
       '1910'=>92228531,'1920'=>106021568,'1930'=>123202660,
       '1940'=>132165129,'1950'=>151325798,'1960'=>179323175,
       '1970'=>203211926,'1980'=>226545805,'1990'=>248709873,
       '2000'=>281421906,'2010'=>308745538);

   $options='';

   while(list($k,$v)=each($years))
   {
    if($select==$v)
    {
    $options.='<option value="'.$v.'"selected>'.$k.'</option>'; 
    }
    else
    {
    $options.='<option value="'.$v.'">'.$k.'</option>';
    }
   }
   return $options;
 } 
 if(isset($_POST['years']))
 {
  $selected= $_POST['years'];

 }

 ?>

<!DOCTYPE html>
<html>
 <head>
  <title>Assignment 5 - kpete7</title>
 </head>
 <body>
     <h1>US Census Population Change Calculator</h1>

 <form action="<?= $_SERVER['PHP_SELF'] ?>" method="POST">
   <h3>Year 1: <select name="year1" >
  <?php echo get_years($selected); ?>
       </select></h3>

       <h3>Year 2: <select name="year2">
  <?php echo get_years($selected); ?>
       </select></h3>
     <input type="submit" name="submit" id="submit" value="Calculate">
  </form>

       <?php   
           if (!empty($year1)) {
           if (is_array($year1)) {
           foreach ($year1 as $key_value => $key) {
              echo $key ;
         }
        ?>
 </body>
</html>

Answer 1

Don't really understand how to write it here as text + keep codeblock intact. 不太了解如何在此处将其编写为文本+保持代码块完整。 :) :)
Is there something similar for php just like jsfiddle? 是否有类似jsfiddle的php类似的东西？

Moved $years array out of function to use it later. 将$ years数组移出函数，以便以后使用。
There were couple variables not set while form was not posted. 没有发布表单时未设置几个变量。
Rewrote your function Used $year1 and $year2 to generate option list and selected values could be different to calcuate population. 重写您的函数使用$ year1和$ year2生成选项列表，并且所选值可能与计算总数不同。
Code indentation was scary. 代码缩进是可怕的。

$years=array(
    1790 => 3929214,
    1800 => 5236631,
    1810 => 7239881,
    1820 => 9638453,
    1830 => 12866020,
    1840 => 17069453,
    1850 => 23161876,
    1860 => 31443321,
    1870 => 38558371,
    1880 => 49371340,
    1890 => 62979766,
    1900 => 76212168,
    1910 => 92228531,
    1920 => 106021568,
    1930 => 123202660,
    1940 => 132165129,
    1950 => 151325798,
    1960 => 179323175,
    1970 => 203211926,
    1980 => 226545805,
    1990 => 248709873,
    2000 => 281421906,
    2010 => 308745538,
);

if (($_SERVER['REQUEST_METHOD']=='POST') && isset($_POST['year1'], $_POST['year2'])) {
    $year1 = (int) $_POST['year1'];
    $year2 = (int) $_POST['year2'];

    echo '<p>Difference of population between selected years: '.abs($year2 - $year1).'</p>';
}
else {
    $year1 = $year2 = reset($years); //default selected
}

function get_years($selected) {
    global $years;
    $options='';
    foreach($years as $k=>$v) {
        $options .= '<option value="'.$v.'"'.($selected==$v ? ' selected="selected"' : '').'>'.$k.'</option>';
    }
    return $options;
}
?>
<!DOCTYPE html>
<html>
<head>
    <title>Assignment 5 - kpete7</title>
</head>
<body>
    <h1>US Census Population Change Calculator</h1>
    <form action="<?php echo $_SERVER['PHP_SELF']; ?>" method="POST">
        <h3>Year 1:
            <select name="year1">
                <?php echo get_years($year1); ?>
            </select>
        </h3>

        <h3>Year 2:
            <select name="year2">
                <?php echo get_years($year2); ?>
            </select>
        </h3>
        <input type="submit" name="submit" id="submit" value="Calculate">
    </form>
</body>
</html>

从PHP的下拉菜单中输出关联数组

问题描述

1 个解决方案

解决方案1
2 已采纳 2018-02-21 23:17:48

从PHP的下拉菜单中输出关联数组

问题描述

1 个解决方案

解决方案1 2 已采纳 2018-02-21 23:17:48

解决方案1
2 已采纳 2018-02-21 23:17:48