Example & Tutorial understanding programming in easy ways.

How many ways can an argument be passed to a subroutine and explain them?

An argument can be passed in two ways. They are passing by value and passing by reference.
 Passing by value: This method copies the value of an argument into the formal parameter of the subroutine.
 Passing by reference: In this method, a reference to an argument (not the value of the argument) is passed to the parameter.