Can not I increase iter2 after erase the object iter2 pointed out previously?

Question

the runtime error happens at the below line. Could you explain why the error happens? Can not I increase iter2 after erase the object iter2 pointed out previously? iter2++; //// error happened

Best regards,

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

int main(void) {

    vector <string> v;

    v.push_back("aaaa");
    v.push_back("bbbb");
    v.push_back("cccc");
    v.push_back("dddd");
    v.push_back("eeee");
    v.push_back("ffff");

    vector<string>::iterator iter2;

    iter2 = v.begin() + 2; 
    v.erase(iter2);
    iter2++;  ////  error happened  

    for (iter2 = v.begin(); iter2 != v.end(); iter2++) {
        cout << *iter2 << " ";
    }

}

no, you cannot. See https://stackoverflow.com/questions/6438086/iterator-invalidation-rules — 463035818_is_not_an_ai, Jul 01 '21 at 09:38

score 1 · Accepted Answer · answered Jul 01 '21 at 09:41

1

Erase function has return value - iterator pointing to the next object in the container. So just use it like this:

iter2=erase(iter2);

Now you can increment it all you want.

answered Jul 01 '21 at 09:41

goodle06

46
6

Since the return value of `erase()` is already the next item of the vector, the increment should not be necessary anymore. – harper Jul 01 '21 at 09:52
@harper, Yes, I made that point, just added that if futher incrementing is needed iter2 is valid iterator for that purpose. – goodle06 Jul 01 '21 at 09:54
1

How does this answer the question - "why the error happens"? – Evg Jul 01 '21 at 10:01
1

wow thanks a lot for all of you answered my questions. – smartrobby Jul 06 '21 at 09:01

Can not I increase iter2 after erase the object iter2 pointed out previously?

1 Answers1