How to get the iterator of the last element?

**Franz** · July 18th, 2002, 04:00 AM

Except using rbegin, are there any other stl functions for getting the iterator of the last element? vector::back just gives me the reference of that.

**Graham** · July 18th, 2002, 04:11 AM

--c.end().

Only works for Bidirectional containers but, then, so does c.rbegin().

**cup** · July 18th, 2002, 04:30 AM

Graham,

Isn't c.end () one past the last one?

**Graham** · July 18th, 2002, 04:36 AM

That's why I applied the decrement operator to it.

**cup** · July 18th, 2002, 04:41 AM

Sorry - I thought the -- was a comment. Ada is getting me confused.

**Franz** · July 18th, 2002, 04:56 AM

If i use decrement operator on the end iterator, will the end iterator "itself" decrease by 1?

Just like
int i = 0;
--i;
Then i will become -1.

May be this is a silly question, sorry.

**Graham** · July 18th, 2002, 05:27 AM

No.

end() simply returns a one-past-the-end iterator and it's that that you decrement.

Code:

std::vector<int> v;

// fill v...

std::vector<int>::iterator i = --v.end();

// i now points to the last element in v.

It would probably be a good idea to check that the container is not empty(), though. Decrementing end() then could cause problems.

**Franz** · July 18th, 2002, 07:18 AM

Oops, VC6 can't compile it.

error C2105: '--' needs l-value

**Graham** · July 18th, 2002, 07:36 AM

OK. Get the interator into a variable and decrement that:

Code:

(whatever)::iterator i = c.end();
--i;

**Franz** · July 18th, 2002, 07:51 AM

Thanks

**Alexey B** · July 18th, 2002, 11:10 AM

You can also write

Code:

(c.end() - 1)

for vector iterators.

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