Question

How do two functions exchange data between them? Compare the two methods of data transfer from calling function to called function.

Answer 1

There are two methods they are call by value and call by reference 

1. call by value:

In call by value method, a copy of the actual parameters are passed to the formal parameters. If the function makes any change it will not affect the original value.

2. call by reference: 

In call by reference method, the reference of the actual parameters are passed to the formal parameters. If the function makes any change it will affect the original value.