[php] Php - testing if a radio button is selected and get the value

I'm using php. I'd like to know how can I test if a radio button is selected and get the value? i can test if the radio button is selected but i cannot get the value. I created a button to test this in my form. First I select a radio button, then i click on the button and it must display a message that says which value i selected and put this value into a variable. In order to test if a radio button is selected i did like this:

$selected_radio=$_POST['SINGLE_' . $question->id . $multi_name_adjust . ''];
if ($selected_radio = 'checked'){}

Thanks

<?php
if (isset($_POST['submit']) and ! empty($_POST['submit'])) {
    if (isset($_POST['radio'])) {
        $radio_input = $_POST['radio'];
        echo $radio_input;
    }
} else {

}
?>
<form action="radio.php" method="post">
   <input type="radio" name="radio" value="v1"/>
   <input type="radio" name="radio" value="v2"/>
   <input type="radio" name="radio" value="v3"/>
   <input type="radio" name="radio" value="v4"/>
   <input type="radio" name="radio" value="v5"/>
   <input type= "submit" name="submit"value="submit"/>
</form>

my form:

<form method="post" action="radio.php">
   select your gender: 
    <input type="radio" name="radioGender" value="female">
    <input type="radio" name="radioGender" value="male">
    <input type="submit" name="btnSubmit" value="submit">
</form>

my php:

   <?php
      if (isset($_POST["btnSubmit"])) {
        if (isset($_POST["radioGender"])) {
        $answer = $_POST['radioGender'];
           if ($answer == "female") {
               echo "female";
           } else {
               echo "male";
           }    
        }else{
            echo "please select your gender";
             }
      }
  ?>

Just simply use isset($_POST['radio']) so that whenever i click any of the radio button, the one that is clicked is set to the post.

 <form method="post" action="sample.php">
 select sex: 
 <input type="radio" name="radio" value="male">
 <input type="radio" name="radio" value="female">

 <input type="submit" value="submit">
 </form>

<?php

if (isset($_POST['radio'])){

    $Sex = $_POST['radio'];
 }
  ?>

A very more efficient way to do this in php:

<form action="#" method="post">
<select name="Color">
<option value="Red">Red</option>
<option value="Green">Green</option>
<option value="Blue">Blue</option>
<option value="Pink">Pink</option>
<option value="Yellow">Yellow</option>
</select>
<input type="submit" name="submit" value="Get Selected Values" />
</form>
<?php
if(isset($_POST['submit'])){
$selected_val = $_POST['Color'];  // Storing Selected Value In Variable
echo "You have selected :" .$selected_val;  // Displaying Selected Value
}
?>

and for check boxes multiple choice:

<form action="#" method="post">
<select name="Color[]" multiple> // Initializing Name With An Array
<option value="Red">Red</option>
<option value="Green">Green</option>
<option value="Blue">Blue</option>
<option value="Pink">Pink</option>
<option value="Yellow">Yellow</option>
</select>
<input type="submit" name="submit" value="Get Selected Values" />
</form>
<?php
if(isset($_POST['submit'])){
// As output of $_POST['Color'] is an array we have to use foreach Loop to display individual value
foreach ($_POST['Color'] as $select)
{
echo "You have selected :" .$select; // Displaying Selected Value
}
?> 

take a look at this code

<form action="result.php" method="post">
Answer 1 <input type="radio" name="ans" value="ans1" /><br />
Answer 2 <input type="radio" name="ans" value="ans2"  /><br />
Answer 3 <input type="radio" name="ans" value="ans3"  /><br />
Answer 4 <input type="radio" name="ans" value="ans4"  /><br />
<input type="submit" value="submit" />
</form>

php

<?php 
if(isset($_POST['submit'])){
if(isset( $_POST['ans'])){  
echo "This is the value you are selected".$_POST['ans'];          
}         
}
?>

It's pretty simple, take a look at the code below:

The form:

<form action="result.php" method="post">
  Answer 1 <input type="radio" name="ans" value="ans1" /><br />
  Answer 2 <input type="radio" name="ans" value="ans2"  /><br />
  Answer 3 <input type="radio" name="ans" value="ans3"  /><br />
  Answer 4 <input type="radio" name="ans" value="ans4"  /><br />
  <input type="submit" value="submit" />
</form>

PHP code:

<?php 

$answer = $_POST['ans'];  
if ($answer == "ans1") {          
    echo 'Correct';      
}
else {
    echo 'Incorrect';
}          
?>

I suggest you do it through the GET request: for example, index.html:

<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.8.3/jquery.min.js"></script>
<form action="result.php" method="post">
  Answer 1 <input type="radio" name="ans" value="ans1" /><br />
  Answer 2 <input type="radio" name="ans" value="ans2"  /><br />
  Answer 3 <input type="radio" name="ans" value="ans3"  /><br />
  Answer 4 <input type="radio" name="ans" value="ans4"  /><br />
  <input type="button" value="submit" onclick="sendPost()" />
 </form>
 <script type="text/javascript">
    function sendPost(){
        var value = $('input[name="ans"]:checked').val();
        window.location.href = "sendpost.php?ans="+value;
    };
 </script>

this is sendpost.php:

<?php
if(isset($_GET["ans"]) AND !empty($_GET["ans"])){
    echo $_GET["ans"];
}
?>