And there's a problem. -

 
  $y ';}? >

In other words, there seems to be nothing wrong with the above code. -What is the specific reason for this error? Or is it a problem with the PHP server setup? Looking for a master, I am a novice

$_POST[C] modified to $_post[' C '], the prompt is this:

Harry

Reply to discussion (solution)

$_post["C"]
$_post["D"]

$_post["C"] all quoted

Thanks for the help, I put $_post[] outside the function, no longer prompt the wrong. Isn't that why?

Unless you block out E_notice level error checking
Otherwise
The associative keys of an array need to be enclosed in quotation marks $_post["C"], $_post["D"]
The assignment of $a, $b is within the conditional branch, and if it's not a form submission, they don't exist.

The correct wording is

 
  $y ';}? >

