如何使用PHP在第一页加载时在下拉列表中设置默认选项 - How to set default choice in drop down list on first page load using PHP?

How to set default choice in drop down list on first page load using PHP?

我用下面的代码创建了一个下拉列表，但我想在第一次加载页面时设置一个默认选项（即，显示最近的日期，而不是第一组选项）。我该怎么做？

<?php
$startyear = ""; 
$startmonth = "";
$startday = "";
$endyear = "";
$endmonth = "";
$endday = "";
$year  = range(1998,2012);
$month = range(01,12);
$day   = range(01,31);
if($_SERVER['REQUEST_METHOD']=='POST')
{
    foreach($_POST as $key=>$value)
    {
        if(is_numeric($value))
        {
            $$key = $value;
        }
    }
}
?>

在这里形成

<form name='update' action='' method='POST'>
Start: <select name='startyear'>
    <?php foreach(array_reverse($year) as $y):?>
    <option value="<?php echo $y?>"<?php echo((isset($startyear) && $startyear == $y)?' selected':null)?>><?php echo $y?></option>
    <?php endforeach;?>
</select>
<select name='startmonth'>
    <?php foreach($month as $m): $m = str_pad($m, 2, "0", STR_PAD_LEFT);?>
    <option value="<?php echo $m;?>"<?php echo ((isset($startmonth) && $startmonth == $m)?' selected':null)?>><?php echo $m;?></option>
    <?php endforeach;?>
</select>
    <select name='startday'>
    <?php foreach($day as $d): $d = str_pad($d, 2, "0", STR_PAD_LEFT);?>
    <option value="<?php echo $d;?>"<?php echo ((isset($startday) && $startday == $d)?' selected':null)?>><?php echo $d;?></option>
    <?php endforeach;?>
</select>
<input type='submit' value='View'/>
</form>

if($_SERVER['REQUEST_METHOD']=='POST')
{
    ...
} else {
    // Set your defaults here.
}

这是你想要的吗？

$cur_day  = date('j');
$cur_mon  = date('n');
$cur_year = date('Y');

然后在期权循环中，类似于

if($y == $cur_year) echo 'selected';

则默认情况下会选择当前年份，对月份和日期也这样做。

由于您的选中检查是这样完成的：

<?php echo ((isset($startday) && $startday == $d)?' selected':null)?>

只需用默认值定义变量，它们就是空的！

$startyear = ""; 
$startmonth = "";
$startday = "";
$endyear = "";
$endmonth = "";
$endday = "";