php 首先回显选定的值
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Echo selected value first
提问by user3080279
I need to echo the selected value first in a form when user wants to make an update. I tried several variants:
当用户想要进行更新时，我需要首先在表单中回显所选值。我尝试了几种变体：
1)
1)
<?php
$opt= array('1' => 'opt1', '2' => 'opt2', '3' => 'opt3') ;
echo '<select name="up_opt" >' ;
foreach ($opt as $i => $value) {
echo "<option value=\"$i\"";
if ($_REQUEST['up_opt'] == $i)
{
echo "selected" ;
}
echo ">$opt[$i]</option>" ;
}
echo '</select>' ;
?>
2)
2)
<?php $opt= array('1' => 'opt1', '2' => 'opt2', '3' => 'opt3') ;
$edu = $_REQUEST['edu'];
<select name="up_opt">
<?php foreach ( $opt as $i=>$opt ) : ?>
<option value="<?php echo $i?>" <?php echo $i == $edu ? 'selected' : ''?>><?php echo $opt ?></option>
<?php endforeach; ?>
</select>
3)
3)
<select name="up_opt">
<option value="1" <?php if ($_GET['1'] == 'option1') { echo 'selected'; } ?>>Opt1</option>
<option value="2" <?php if ($_GET['2'] == 'option2') { echo 'selected'; } ?>>Opt2</option>
<option value="3" <?php if ($_GET['3'] == 'option3') { echo 'selected'; } ?>>Opt3</option>
</select>
None of these variants echoes the checked value first. Can someone help me, tell me what is wrong or give me another variant?
这些变体中没有一个首先响应检查的值。有人可以帮助我，告诉我有什么问题或给我另一个变体吗？
回答by Hast
Variant 3 is ok (but I'd rather use a loop instead of hard-coded options). Your mistake is that you compare 'option1', 'option2' and so one when your real values are '1', '2', '3'. Also as @ElefantPhace said, don't forget about spaces before selected, or you'll get invalid html instead. So it would be this:
变体 3 没问题（但我宁愿使用循环而不是硬编码选项）。你的错误是当你的实际值为“1”、“2”、“3”时，你比较了“选项1”、“选项2”等。同样正如@ElefantPhace 所说，在selected之前不要忘记空格，否则你会得到无效的 html。所以它会是这样的：
<select name="up_opt">
<option value="1" <?php if ($_GET['up_opt'] == 1) { echo ' selected="selected"'; } ?>>Opt1</option>
<option value="2" <?php if ($_GET['up_opt'] == 2) { echo ' selected="selected"'; } ?>>Opt2</option>
<option value="3" <?php if ($_GET['up_opt'] == 3) { echo ' selected="selected"'; } ?>>Opt3</option>
</select>
With loop:
带循环：
<?php
$options = array(
1 => 'Opt1',
2 => 'Opt2',
3 => 'Opt3',
);
?>
<select name="up_opt">
<?php foreach ($options as $value => $label): ?>
<option value="<?php echo $value; ?>" <?php if ($_GET['up_opt'] == 1) { echo ' selected="selected"'; } ?>><?php echo $label; ?></option>
<?php endforeach ?>
</select>
回答by ElefantPhace
Here is all three of your variants, tested and working as expected. They are all basically the same, you were just using the wrong variable names, and different ones from example to example
这是您的所有三个变体，经过测试并按预期工作。它们基本上都是一样的，你只是使用了错误的变量名，并且每个例子都有不同的变量名
1)
1)
<?php
$opt= array('1' => 'opt1', '2' => 'opt2', '3' => 'opt3') ;
echo '<select name="up_opt">';
foreach ($opt as $i => $value) {
echo "<option value=\"$i\"";
if ($_POST['up_opt'] == $i){
echo " selected";
}
echo ">$value</option>";
}
echo '</select>';
?>
2) uses same array as above
2) 使用与上面相同的数组
$edu = $_POST['up_opt'];
echo '<select name="up_opt">';
foreach ( $opt as $i => $value ){
echo "<option value=\"$i\"", ($i == $edu) ? ' selected' : '';
echo ">$value</option>";
}
echo "</select>";
3)
3)
echo '<select name="up_opt">';
echo '<option value="1"', ($_POST['up_opt'] == '1') ? 'selected':'' ,'>Opt1</option>';
echo '<option value="2"', ($_POST['up_opt'] == '2') ? 'selected':'' ,'>Opt2</option>';
echo '<option value="3"', ($_POST['up_opt'] == '3') ? 'selected':'' ,'>Opt3</option>';
echo '</select>';
