What's the use of the third, environment variable argument to the C++ main()?

Question

I have come to understand that char **envp is the third argument to main, and with the help of the code below, I was able to see what it actually c

Answer 1

This is typically used to set configuration options or other information for a whole group of programs. Another use is to specify environment settings for a particular machine or user setup.
Well known examples are the PATH variable that contains the lookup pathes for executables, or the LD_LIBRARY_PATH variable that contains the pathes where to lookup the shared libraries.