Question

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Difference between pointer variable and reference variable in C++

As I am starting with C++, I found the operation below confusing. I got to know about passing by reference and passing by value. But recently I came across functions like this which confused me:

Func1(int &a)
Func2(int *a)

Both of the functions expect the address of a, but when I call Func1 I do that by Func1(a) and in case of Func2, I call by Func2(&a).

How come Func1 is accepting int a directly while it is expecting the address of a?

Answer 1

Func1(int &a)
// It accepts arguments by reference.
// Changes to an inside Func1 are reflected in the caller.
// 'a' cannot bind to an Rvalue, e.g., it can't call Func1(5)
// 'a' can never be referring to something that is not a valid object

Func2(int *a)
// It accepts arguments by value.
// Change to an inside Func1 is not reflected in the caller, and changes to *a are
// 'a' can bind to an Rvalue, e.g., Func1(&localvar).
// 'a' can be NULL. Hence Func2 may need to check if 'a' is NULL.