传递给php文件的HTML文本字段值为null [关闭]

I have an html code that passes the values of text fields to a php file. To check for the value of these variables , I use echo to print the values but nothing gets printed.

This is my html code:

 <form action="connect.php" type="post">
   Username: <input type="text" name = "uname"><br>
   Confirm Username: <input type="text" name = "cuname"><br>
   Password: <input type="password" name = "pword"><br>
   Confirm Password: <input type="password" name="cpword"><br>
   <input type="submit" value="Sign up">
 </div>
 </form>

This is my connect.php code:

<?php
  $info1 = isset($_POST['uname']);
  $info2 = isset($_POST['cuname']);
  $info3 = isset($_POST['pword']);
  $info4 = isset($_POST['cpword']);

  echo $info1;
  echo $info2;
  echo $info3;
  echo $info4;
?>

isset() is a boolean function that tells you if a variable is set or not. If you want to print the value itself, try:

$info1 = $_POST['uname'];
echo $info1;

If you want to see what comes from the function, try debugging with:

print_r($_POST);

a) correct:

<form action="connect.php" type="post"> 
to   <form action="connect.php" method="post">

b) mostly, you don't "pass the values of text fields to a php file", you are trying to output the input at screen. If you want to save and reuse them, you have to use a database.

<form action="connect.php" method="POST">
   Username: <input type="text" name = "uname"><br>
   Confirm Username: <input type="text" name = "cuname"><br>
   Password: <input type="password" name = "pword"><br>
   Confirm Password: <input type="password" name="cpword"><br>
   <input type="submit" value="Sign up">
 </div>
 </form>

the php....

  <?php
  if (isset($_POST['submit'])) //if form submitted...
    {
  $info1 = $_POST['uname']; // Get POST value
  $info2 = $_POST['cuname'];
  $info3 = $_POST['pword'];
  $info4 = $_POST['cpword'];

  echo $info1;
  echo $info2;
  echo $info3;
  echo $info4;
  }
?>

To avoid errors like Undefined index you can always use the at sign (@)

<?php
  $info1 = @$_POST['uname'];
  $info2 = @$_POST['cuname'];
  $info3 = @$_POST['pword'];
  $info4 = @$_POST['cpword'];

  echo $info1;
  echo $info2;
  echo $info3;
  echo $info4;
?>