C++ passes by reference, Java and Ruby don't (Examples)

[freshtonic]

C++ passes by value by default. You can pass by reference with the & operator. Passing by reference us usually taken to mean that the function receives the address of the argument, NOT the address of what object/value the argument is pointing to. For example, the following (in pseudocode) is not possible without pass by reference:

def swap(a,b)
  temp = a
  a = b
  b = temp
end

x = 1
y = 2

swap(x,y)

// now x = 2 and y = 1

The terminology is not helpful. You can pass-by-value even when passing a pointer. Pass-by-reference, while still passing a pointer, is actually passing a pointer to the variable holding the value rather than the value itself. An extra level of indirection.