CODEWITHSUNDEEP
c++vector
user8255177
user8255177

Reputation:

Vector erase elements from range

Why programm stopped? That programm compile, but if i run, that he break, and give some message about iterator vector not incrementable. What is wrong?

int main() 
{
    std::vector<int> vec;
    for (int i = 1; i <= 100; ++i)
        vec.push_back(i);
    for (auto itr = vec.begin() + 5; itr < vec.end() - 5; ++itr)
        vec.erase(itr);
    for (const auto& itr : vec)
            std::cout << itr << std::endl;
    return 0;
}

Upvotes: 2

Views: 392

Answers (2)

jodag
jodag

Reputation: 22184

If you want to erase elements in the vector using a for loop you can do so by iterating backwards through the set of elements. For example

#include <vector>
#include <iostream>
int main()
{
    std::vector<int> vec;
    for (int i = 0; i <= 100; ++i)
        vec.push_back(i);
    for (auto itr = vec.end() - 6; itr > vec.begin() + 4; --itr)
        vec.erase(itr);
    for (const auto& itr : vec)
        std::cout << itr << std::endl;
    return 0;
}

As pointed out by 21koizyd, if you want to erase a range of elements you can use the second argument of std::vector::erase to specify an end element.

Upvotes: 2

21koizyd
21koizyd

Reputation: 1993

You are wrong, because function erase don't anull iterators. So you can do like that:

auto itr = vec.begin() + 5;
while (itr != vec.end() - 5) {
itr = vec.erase(itr);
}

or more flexible ( without loop )

vec.erase(vec.begin() + 5, vec.end() - 5);

Upvotes: 4

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