是否可以将下拉列表中的第一项默认为空白并选中，但当在下拉列表中选择一项并点击提交时，该值保留在那里
这里有一个例子
<form action="" method="post" />
<SELECT NAME="whatever" id="whatever">
<?php $selected = isset($_POST["whatever"]) && $_POST["whatever"] == 'whatever'; ?>
<option value="" hidden="true" selected="selected"></option>
<OPTION VALUE=1 onclick"selected='selected'">All</OPTION>
</SELECT>
<input type="submit" name="submit" value="Update"/>
</form>
当前如果我点击提交，它会把选中的值变回空白
你可以这样使用
<form action="" method="post" />
<SELECT NAME="whatever" id="whatever">
<option value="">Select value</option>
<OPTION VALUE=1 <?php if($_POST["whatever"]==1) echo "selected='selected'";?> >All</OPTION>
<OPTION VALUE=2 <?php if($_POST["whatever"]==2) echo "selected='selected'";?> >Value One</OPTION>
</SELECT>
<input type="submit" name="submit" value="Update"/>
</form>
function html_select($name, $options, $selected= "")
{
// open <select> tag, set id & name attributes
$select = "<select id='"$name'" name='"$name'">'n";
// populate options to drop down list
foreach ($options as $value=> $html) {
$select .= "<option value='"$value'"";
// select the selected option
if ($value == $selected) {
$select .= " selected='"selected'"";
}
$select .= ">$html</option>'n";
}
// close </select> tag
$select .= "</select>";
// return element
return $select ;
}
echo html_select("whatever", array("" => "Select Value", "1" => "Value 1"), $_POST["whatever"]);