注意：未定义索引：在C：\ xampp \ htdocs \ cars \ index1.php中的elegido在线

Question

i have a dynamic SELECT category menu, i get this error Notice: Undefined index: elegido in C:\xampp\htdocs\cars\index.php on line 30 , 40 & 48 what makes the menu does not work properly.

WHAT IS CAUSING THIS ERROR?

LINES 30, 40 & 48:

 30 if ($_POST["elegido"]==1) {
 40 if ($_POST["elegido"]==2) {
 48 if ($_POST["elegido"]==3) {

HERE IS ALL THE CODE

<script ="javascript">
$(document).ready(function(){
   $("#marca").change(function () {
           $("#marca option:selected").each(function () {
            elegido=$(this).val();
            $.post("modelos.php", { elegido: elegido }, function(data){
            $("#modelo").html(data);
            });            
        });
   })
});
</script>
<p>Marca: 
<select name="marca" id="marca">    
    <option value="1">Renault</option>
    <option value="2">Seat</option>
    <option value="3">Peugeot</option>    
</select></p>
<p>Modelo:
<select name="modelo" id="modelo">    
    <option value="1">4</option>
    <option value="2">5</option>
    <option value="3">7</option>
    <option value="4">21</option>
    <option value="5">Scennic</option>
    <option value="6">Traffic</option>
</select></p>
<?php
$options="";
if ($_POST["elegido"]==1) {
    $options= '
    <option value="1">4</option>
    <option value="2">5</option>
    <option value="3">7</option>
    <option value="4">21</option>
    <option value="5">Scennic</option>
    <option value="6">Traffic</option>
    ';    
}
if ($_POST["elegido"]==2) {
    $options= '
    <option value="1">Ibiza</option>
    <option value="2">Toledo</option>
    <option value="3">Cordoba</option>
    <option value="4">Arosa</option>
    ';    
}
if ($_POST["elegido"]==3) {
    $options= '
    <option value="1">106</option>
    <option value="2">206</option>
    <option value="3">306</option>
    ';    
}
echo $options;    
?>

Answer 1

try this

if (isset($_POST["elegido"])) {

//your code

}