Want to delete a vector from another vector in C++

Asked Oct 04 '16 at 13:29

Active Oct 04 '16 at 14:31

Viewed 31 times

I am trying to delete a vector list from another vector list but the program stops responding as soon as I reach the specific part of the program.Here is the program:

#include<iostream>
#include<vector>
#include<iterator>
int main(){
    using namespace std;
    vector<int> a(5);
    int ints[3] = {2,3,5};
    vector<int> b(ints,ints+3);
    for(int i=0; i<5; i++){
        a[i] = i+1;
    }
    vector<int> :: iterator pra;
    vector<int> :: iterator prb;
    cout << "initial list:";
    for(pra = a.begin(); pra!=a.end(); pra++){
        cout << *pra << " ";
    }
    cout << endl;
    for(pra = a.begin(); pra!=a.end(); pra++){
        for(prb = b.begin(); prb!=b.end(); prb++){
            if(*pra == *prb){
                cout << *pra << " ";
                a.erase(pra);
                b.erase(prb);
                break;
            }
        }
    }

    cout << " Final List:"; 
    for(pra = a.begin(); pra!=a.end(); pra++ ){
        cout << *pra << " ";
    }

}

edited Oct 04 '16 at 14:31

Ahmad Khan

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asked Oct 04 '16 at 13:29

Sid

where is the "specific part"? please add this to your question. – apple apple Oct 04 '16 at 13:31
You really need to read more about [the `erase` member function](http://en.cppreference.com/w/cpp/container/vector/erase), especially the part that says that later iterators (including `end()`) will be invalidated, and what the function returns. – Some programmer dude Oct 04 '16 at 13:32
Oh and since C++11 you don't need the `ints` array, you can initialize a vector directly as `std::vector b = { 2, 3, 5};` – Some programmer dude Oct 04 '16 at 13:33
@appleapple: If i comment out the two erase statements, then the code works fine. I think there's some problem in those statements. – Sid Oct 04 '16 at 14:51
@Sid yes, and like others said, `erase(it)` invalidate any iterator after `it` (contains `it` itself) – apple apple Oct 04 '16 at 15:08
@JoachimPileborg. Thanks for the help – Sid Oct 04 '16 at 15:09
@appleapple Yeah right. BTW how to accomplish it then? – Sid Oct 04 '16 at 15:11
you can use the return value of `erase` – apple apple Oct 04 '16 at 15:13

Want to delete a vector from another vector in C++

0 Answers0