Difference between pass-by-reference & and * ?

Question

What is the difference between passing-by-reference and using the C pointer notation?

void some_function(some_type& param)

and

void some_function(some_type *param)

Thanks

Answer 1

• You can't get a NULL reference: this alone gives you lots of safety
• You can treat your reference as if it was an object: you can dereference it or whatever you need.

Basically you handle a safe pointer as if it was your own object.

Answer 2

Syntactic sugar.

When you pass a pointer to a variable in a subroutine call, the address of that variable is passed to the subroutine. To access the variable in the subroutine, the pointer has to be dereferenced.

When you pass a reference to a variable, the compiler takes care of obtaining the address of the variable when the variable is passed to the subroutine and dereferencing the variable in the subroutine.

Answer 3

A pointer can be repointed to a new object, but a reference cannot.

void MyFunction (MyType *myParameter)
{
    myParameter = new MyType ("BoogaBoogaBooga");
}

void main ()
{
    MyType *myArgument = new MyType ("WonkaWonkaWonka");
    MyType *myCopy = myArgument;

    MyFunction (myArgument);

    //myArgument is now pointing to the BoogaBoogaBooga object, but
    //myCopy is still pointing to the WonkaWonkaWonka object
}

Also, as others have already mentioned, a null pointer could be passed in, but a null reference could not be. Calling by reference provides nice syntactic sugar for accessing the provided object's members.