this is the code for HTML:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title></title>
</head>
<body>
<center>
<form action="welcom.php" method="post" />
:<input type="text" name="name" />
<br />
:<input type="text" name="birthday" />
<br />
<input type="submit" />
</form>
</center>
</body>
</html>this is the code for PHP:
<!DOCTYPE html>
<html lang="zh-cn">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta http-equiv="X-UA-Compatible" content="ie=edge">
<title>Document</title>
<body>
Welcome <?php echo $_POST["name"]; ?><br />
Your birthday is: <?php echo $_POST["birthday"]; ?>
<?php echo var_export($_PSOST); ?>
</head>
</body>
</html> after submitting the form, the information I entered is not displayed. 
localhost:
how to solve these problems?