Remove Element from std::vector<std::string> >

Question

My compiler complains.

#include <iostream>
#include <vector>
using namespace std;

int main(){

        vector<string> vec[2];
        vec[0].push_back("test1");
        vec[0].push_back("test2");

        cout << vec[0][0] << endl;
        vec[0].erase(vec.begin());
        cout << vec[0][1] << endl;

}

What is wrong when I call erase?

Answer 1

vec is an array of vector<string> s. I believe you meant vec[0].begin() like so:

vec[0].erase(vec[0].begin());

Answer 2

    vec[0].erase(vec[0].begin());
    cout << vec[0][1] << endl;

After you erased the first element, there's only one left. This one element is at position 0, which means index 1 is off bounds -> undefined behaviour.