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Are these the same:
int foo(bar* p) { return p->someInt(); } and
int foo(bar& r) { return r.someInt(); } Ignore the null pointer potential. Are these two functions functionally identical no matter if someInt() is virtual or if they are passed a bar or a subclass of bar?
Does this slice anything:
bar& ref = *ptr_to_bar; 
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Pointers: A pointer is a variable that holds the memory address of another variable. A pointer needs to be dereferenced with the * operator to access the memory location it points to. References: A reference variable is an alias, that is, another name for an already existing variable.
Appearances aside, const pointers differ from references in one subtle but significant way. A valid reference must refer to an object; a pointer need not. A pointer, even a const pointer, can have a null value. A null pointer doesn't point to anything.
Pointers are variables; they contain the address of some other variable, or can be null. The important thing is that a pointer has a value, while a reference only has a variable that it is referencing.
The difference between pass-by-reference and pass-by-pointer is that pointers can be NULL or reassigned whereas references cannot. Use pass-by-pointer if NULL is a valid parameter value or if you want to reassign the pointer. Otherwise, use constant or non-constant references to pass arguments.
C++ references are intentionally not specified in the standard to be implemented using pointers. A reference is more like a "synonym" to a variable than a pointer to it. This semantics opens some possible optimizations for the compiler when it's possible to realize that a pointer would be an overkill in some situations.
A few more differences:
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