Can't retrieve radio button values from multiple radio groups - radio-button

Question

In my form, I have x groups of radio buttons generated:
for ( $j = 0; $j < $x; $j++ ) {
<input type="radio" name="gender<?php echo $x; ?>" value="male" />Male
<input type="radio" name="gender<?php echo $x; ?>" value="female" />Female
...
}
When, after submit, I try to retrieve these values:
for ( $j = 0; $j < $x; $j++ ) {
echo $_POST['gender'.$j];
...
}
I get these error messages:
Notice: Undefined index: gender0 in ...
Notice: Undefined index: gender1 in ...
Notice: Undefined index: gender2 in ...
Yet I see these radio groups in my markup correctly defined:
<input type="radio" value="male" name="gender0">Male
<input type="radio" value="female" name="gender0">Female
...
<input type="radio" value="male" name="gender1">Male
<input type="radio" value="female" name="gender1">Female
So why these error messages?

Answer 1

Just make a var_dump($_POST); on the beginning of your receiving script, then you’ll see exactly what you get.
And you are aware that you get values only for radio buttons that are actually checked, right?
So if you can not be certain if the user will have a radio button checked per group, then check whether that POST entry is available before accessing it, using isset or empty.
Btw., an even more convenient way to deal with data like this, is to name the form fields in a way that gets you an array in PHP in the first place:
<input type="radio" name="gender[0]" value="male" />Male
<input type="radio" name="gender[0]" value="female" />Female
<input type="radio" name="gender[1]" value="male" />Male
<input type="radio" name="gender[1]" value="female" />Female
– that will get you an array in $_POST['gender'], that you can loop through with a foreach loop like this:
if(isset($_POST['gender']) && is_array($_POST['gender'])) {
foreach($_POST['gender'] as $index => $value) {
// …
}
}