Radio Buttons in PHP

Let's now learn how to work with radio in PHP. Let's make several radio buttons in our form:

html<form action="" method="GET">
  <input type="radio" name="radio" value="1">
  <input type="radio" name="radio" value="2">
  <input type="radio" name="radio" value="3">
  <input type="submit">
</form>

After submitting the form, the $_GET array will contain the value of the value attribute of the selected radio button, or null, if nothing was selected:

html<?php
  var_dump($_GET['radio']); // '1', '2', '3' or null
?>

When working with radio buttons, the same problem arises as with checkboxes. To solve this problem, let's add a hidden input:

html<form action="" method="GET">
  <input type="hidden" name="radio" value="0">
  <input type="radio"  name="radio" value="1">
  <input type="radio"  name="radio" value="2">
  <input type="radio"  name="radio" value="3">
  <input type="submit">
</form>

You can also avoid introducing a hidden input by making one of the radio buttons selected by default:

html<form action="" method="GET">
  <input type="radio" name="radio" value="1" checked>
  <input type="radio" name="radio" value="2">
  <input type="radio" name="radio" value="3">
  <input type="submit">
</form>