function main( ) invokes other functions within it.It is the first
function to be called when the program starts execution.
It is the starting function
It returns an int value to the environment that called the program
Recursive call is allowed for main( ) also.
It is a user-defined function
Program execution ends when the closing brace of the function main(
) is reached.
It has two arguments 1)argument count and 2) argument vector
(represents strings passed).
Any user-defined name can also be used as parameters for main( )
instead of argc and argv