PHP is not recognized as an internal or external command in command prompt

Question

I am getting this error when I run the command in PHP:

C:\xampp\htdocs>php
'php' is not recognized as an internal or external command,
operable program or batch file.

When I run the command in this path, it doesn't give an error.

C:\xampp\php>php  //do not got error here

Why am I getting this error? and how can I solve this?