C++ Terminology Reference and Iterator

Question

Wikipedia tells me that

Reference is a simple reference datatype that is less powerful but safer than the pointer type inherited from C

I am learning C++ and I came across the function vector::front().

In the documentation it says the fuction

Returns a reference to the first element in the vector.

However, as shown in the code below, the return value is treated as not the reference but the element itself.

vector<int> my_vector(1); // initialising a vector
my_vector.push_back(10); // inserting 10
int number = my_vector.front() + 1; // number = 11

If my_vector.front() is a reference to the first element, shouldn't it be dereferenced with (*) in order to access the value?

Seeing that

*my_vector.begin() == my_vector.front() == 10

and I can do arithmetics to the iterator, should I think of iterators as something similar to pointers in C, and think of reference as a value?

Also, this answers your question about iterators vs pointers: [How are iterators and pointers related?](http://stackoverflow.com/q/2728190/3425536) — Emil Laine, Feb 14 '16 at 13:46

score 3 · Accepted Answer · answered Feb 14 '16 at 13:24

3

... should I think of iterators as something similar to pointers in C, and think of reference as a value?

Yes, iterators implement pointer like behavior.

Think of references as alias for a specific value stored.

answered Feb 14 '16 at 13:24

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score 2 · Answer 2 · answered Feb 14 '16 at 13:25

my_vector.front() returns, as you already stated, a reference to the first element, not an iterator/pointer. References do not need to be dereferenced in order for their values to be used.

and I can do arithmetics to the iterator, should I think of iterators as something similar to pointers in C, and think of reference as a value?

Exactly. Iterators are basically glorified pointers used for container access while references are more or less *pointer (dereferenced pointers).

Christophe · Answer 3 · 2016-02-14T13:35:36.397

When an object is passed or returned by reference, using this reference is like using the original object itself (including modifying it !). Try for example:

...
my_vector.front() = number *2; 
cout << number<<" "<<  my_vector.front() <<endl;

Iterators are pointer like. You have to dereference them (with * or ->) to access to the object it refers to. The arithmetic possibilities depend however strongly on the kind of iterator and might be much more limited than for pointers:

my_vector.begin()+10    // ok for a random access iterator on vectors, not for 
                        // bidirectional iterators on iterators on a list

C++ Terminology Reference and Iterator

3 Answers3