The data submitted by the form in php is displayed on another page, and the blank space is displayed ??

I am a beginner in PHP. I submitted data to post_data.php using the form in post.html. It is blank and no value is passed. Why ?? The Code is as follows: post.html {code...} the code of post_data.php is as follows: {code...} running result: the page has not passed the message...

I am a beginner in PHP. I submitted data to post_data.php using the form in post.html. It is blank and no value is passed. Why ??
The Code is as follows:
Post.html

The post_data.php code is as follows:

 
  "; Echo" z1 = $ a1, z2 = $ a2 "; echo"
  "; Var_dump ($ _ post);} The else {echo" Page has no value !! ";}

Running result:
No page value passed in

File Path:

Please help me see ???

Reply content:

I am a beginner in PHP. I submitted data to post_data.php using the form in post.html. It is blank and no value is passed. Why ??
The Code is as follows:
Post.html

The post_data.php code is as follows:

 
  "; Echo" z1 = $ a1, z2 = $ a2 "; echo"
  "; Var_dump ($ _ post);} The else {echo" Page has no value !! ";}

Running result:
No page value passed in

File Path:

Please help me see ???

As instructed by asmair, I modified the code and displayed it successfully.
Post.html is as follows:

Post_data.php is as follows:

  "; Echo" z1 = $ a1, z2 = $ a2 "; echo"
  "; Var_dump ($ _ POST);} The else {echo" Page has no value !! ";}?>

I am a newbie and have made low-level mistakes.

Method = "post" cannot contain commas,
$ _ POST [... should be capitalized.