The values in the PHP array cannot be taken out. What to do with it

The values inside the PHP array cannot be taken out.
After submitting the form with post:
Var_dump ($_post);
The value of the output post array can be seen:
Array (Ten) {["Picname"]=> Array (2) {[0]=> string ("P_large_18sq_6bcc000198902d14.jpg" [1]=> string "P_") Large_4u3y_64f80006f4305c40.jpg "} [" P_large_18sq_6bcc000198902d14_jpgtop "]=> string (5)" 290px "[" P_large_18sq_ 6bcc000198902d14_jpgleft "]=> string (5)" 454px "[" P_large_18sq_6bcc000198902d14_jpgheight "]=> string (3)" 236 "[ "P_large_18sq_6bcc000198902d14_jpgwidth"]=> string (3) "["] ["P_large_4u3y_64f80006f4305c40_jpgtop"]=> String (5) "100px" ["P_large_4u3y_64f80006f4305c40_jpgleft"]=> string (5) "500px" ["p_large_4u3y_64f80006f4305c40_ Jpgheight "]=> string (3)" ["P_large_4u3y_64f80006f4305c40_jpgwidth"]=> string (3) "[" num "]=> string ( 1) "2"}

But then remove the value from the POST, for example _post["P_large_18sq_6bcc000198902d14.jpgtop"]
You will get an error: notice:undefined index:p_large_18SQ_6bcc000198902d14.jpgtop
But ya in _post inside ah this is for God horse Ah = =| | | | |

------Solution--------------------
Yes, the "." in the variable name of the commit will become "_"

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