biplab3/gist:67afd2ec97ab12cd47ac77cd4c25b3cd

## gistfile1.txt
<html>
<body>

<form method="post" action="<?php echo $_SERVER['PHP_SELF'];?>">
  Name: <input type="text" name="username">
  <input type="submit" name="save" value="submit">
</form>

<?php
if ($_SERVER["REQUEST_METHOD"] == "POST") {
    // collect value of input field
    $username = $_REQUEST['username'];
    if (empty($username)) {
        echo "Username is empty";
    } else {
        echo $username;
    }
}
?>
</body>
</html>

or

<html>
<body>
<form method="post" action="">
  Name: <input type="text" name="username">
  <input type="submit" name="save" value="submit">
</form>
</body>
</html>

<?php
if (isset($_POST['save']) //here 'save' is the name attribute of the button field
   {
    // collect value of input field
    $username = $_POST['username'];//here username is the field name of the input type element

	echo $username;

}
?>
	<html>
	<body>

	<form method="post" action="<?php echo $_SERVER['PHP_SELF'];?>">
	Name: <input type="text" name="username">
	<input type="submit" name="save" value="submit">
	</form>

	<?php
	if ($_SERVER["REQUEST_METHOD"] == "POST") {
	// collect value of input field
	$username = $_REQUEST['username'];
	if (empty($username)) {
	echo "Username is empty";
	} else {
	echo $username;
	}
	}
	?>
	</body>
	</html>

	or

	<html>
	<body>
	<form method="post" action="">
	Name: <input type="text" name="username">
	<input type="submit" name="save" value="submit">
	</form>
	</body>
	</html>

	<?php
	if (isset($_POST['save']) //here 'save' is the name attribute of the button field
	{
	// collect value of input field
	$username = $_POST['username'];//here username is the field name of the input type element

	echo $username;

	}
	?>