CODEWITHSUNDEEP
c++visual-c++vectoriterator
Jack
Jack

Reputation: 3799

Vector Iterators Incompatible when in class

I've got a pretty simple class with a vector as a private variable like so:

#include "Zombie.h"
#include <vector>

class CGame{
public:
CGame();
void DoVectorStuff();
private:
std::vector<Zombie> zombies;
};

In the function DoVectorStuff() im just looping through the vector like so:

for(std::vector<Zombie>::iterator it = zombies.begin(); it != zombies.end(); ++it)
{
   it->Update(delta);
}

Which is causing Visual Studio 2010 to give me a debug assertion when I run it. The same code worked fine when it was in a function by itself, I assume its something to do with me adding it to a class but I can't figure out what.

EDIT: https://i.sstatic.net/2K9GY.png This is the error I'm getting.

Upvotes: 1

Views: 2177

Answers (3)

Robᵩ
Robᵩ

Reputation: 168616

Wild Guess: Zombie::Update updates, among other things, the zombies vector, invalidating the iterator it. Do zombies die or reproduce during their Update cycle?

Upvotes: 1

parapura rajkumar
parapura rajkumar

Reputation: 24403

The assertion you are getting vector iterators imcompatible indicates that you are trying to compare iterators from different vectors.

Typically you can get these by

POSSIBILITY 1

std::vector<int> foo( 100 );
std::vector<int> bar( 100 );

for( std::vector<int>::iterator iter = foo.begin();
    iter != bar.end();
    ++iter )
{
    std::cout << *iter;
}

Notice the above code and you will notice that I am comparing iter that is a iterator from foo vector to bar.end()

POSSIBILITY 2

Another way you can get the same error is by hanging on to invalid iterators.

std::vector<int> foo( 3 );
std::vector<int>::iterator enditer = foo.end();

foo.push_back( 3 );
foo.push_back( 3 );
foo.push_back( 3 );  // can invalidate endIter above


for( std::vector<int>::iterator iter = foo.begin();
    iter != enditer;
    ++iter )
{
    std::cout << *iter;
}

Notice how in the above code I have hanged on to endIter which can be invalidated by adding more elements to foo

Upvotes: 2

Tom Knapen
Tom Knapen

Reputation: 2277

Try to use

std::vector<Zombie>::iterator

instead of 

std::vector::iterator

Upvotes: 0

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