Error "vector iterators incompatible" when concatenating two STL vectors

Question

Following the advice on this question, I am attempting to do just that. However, at runtime I get an error "vector iterators incompatible", in the following:

std::vector<SE> all;
all.insert(all.end(),p->ev.begin(),p->ev.end());

where class pointed to by p contains a member

std::vector<SE> ev;

It is possible for the vector ev to be empty, in which case I want 'all' to be unchanged. Otherwise, I want all the elements of p->ev to be added to 'all', in the same order, at the end of 'all'.

What am I doing wrong?

Visual Studio 2010 C++, 32-bit Windows XP

ADDITIONAL INFO: Using the debugger, I have traced the proximate cause of the error message as the "owning container" of p->ev.begin() being 0. I have no clue what the "owning container" means.

The error message is, in its entirety, "vector iterators incompatible". — Woody20, Jul 04 '13 at 04:12
Can you provide class `p` points to definition and how do you create p? So far it looks like `p` wasn't property initialised. — alexrider, Jul 04 '13 at 06:38
class P{std::vector ev}. Creating p is in the class containing all.insert; it has a member 'P pArray[300]'. I know p is valid because I can see its data in debugger. Also, p->ev.begin shows the correct SE from class P in the debugger. — Woody20, Jul 04 '13 at 17:00
@Woody20: In Visual Studio, the "Error Window" shows error _summaries_. The full error text can be found in the "Output Window". — Mooing Duck, Jan 26 '17 at 21:11

rreeves · Answer 1 · 2013-07-03T23:26:19.767

0

My first thought is to try something like this

if(!p->ev.isEmpty())
{
   foreach(SE record in p->ev)
   {
      all.insert(SE);
   }
}

UPDATE: I didn't see you link at first, but will leave my anwser.

edited Jul 03 '13 at 23:26

answered Jul 03 '13 at 23:14

rreeves

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I want to know why insert isn't working as advertised. I know there are other ways to accomplish the task. – Woody20 Jul 04 '13 at 04:13

score 0 · Answer 2 · answered Jul 03 '13 at 23:19

0

I tried this and it seemed to work ok

#include <vector>
#include <iostream>

struct P {
    P() {
        ev.push_back(3);
        ev.push_back(4);
    }
    std::vector<int> ev;
};

int main(int argc,char** argv) {
    std::vector<int> all;
    all.push_back(1);
    all.push_back(2);

    P* p = new P();
    all.insert(all.end(),p->ev.begin(),p->ev.end());
    copy(all.begin(),all.end(),std::ostream_iterator<int>(std::cout));
        delete p;
    return 0;
}

The only thing I could thing of giving that error would be if the SE type is redefined somewhere (maybe a typedef?). For the above example using basic types there shouldn't be an issue.

Produces 1,2,3,4 in order. If ev is empty, then we get 1,2 as you asked

answered Jul 03 '13 at 23:19

Delta_Fore

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One difference is that you made ev a vector of ints, rather than of SEs. SE is a structure with several int and float members, and one member which is an array of structs--nothing complicated. SE is defined in only one place, and not used in any typedefs. Another difference is that as shown in my code, 'all' starts out empty. – Woody20 Jul 04 '13 at 04:17
The algorithms on std library don't differentiate on type so it won't matter whether it's int or some other structure as long as it's the same in all cases. Also whether 'all' is empty or not wont make a difference for an insert() as all.end() is the position whether you are inserting – Delta_Fore Jul 04 '13 at 07:20
I didn't expect either of these should matter, but I thought I would mention them. Visual Studio uses something called "Checked-Iterators" ([here](http://www.codeproject.com/Articles/17745/Checked-Iterators)), and it's this feature that generates the error message. Were you using Visual Studio when you tried this? – Woody20 Jul 04 '13 at 17:04

score 0 · Answer 3 · answered Jul 05 '13 at 17:17

Apparently this is a bug in Visual Studio 2010.

Visual Studio has a feature "Checked Iterators". In a debug build, every iterator operation is chacked at runtime for errors, e g, out of range. My pgm failed one of these checks, namely, that the iterators for the range for the vector being inserted were from the same collection class (i e, in this case, from the same vector). As you can see from my code sample, they were, so the test result was incorrect.

The test worked correctly if the vector being inserted (p->ev in my example) was in the same class as the destination vector ('all'), but not if the vector being inserted was in a different class. That's one reason why Ronnie didn't see the problem, even if he was using VS 2010.

For anyone who may run into this same difficulty, the "cure" is to disable the iterator checking, by defining C++ preprocessor variable _ITERATOR_DEBUG_LEVEL as 0. The Microsoft documentation on use of _SECURE_SCL for this purpose is incorrect.

With checking disabled, everything works as expected.

A similar bug was reported, and allegedly fixed, in VS 2010 in connection with 'erase'.

Error "vector iterators incompatible" when concatenating two STL vectors

3 Answers3