CODEWITHSUNDEEP
c++vector
DomX23
DomX23

Reputation: 887

Removing an element from the vector without removing the elements after

Coming from Java and using the ArrayList class has me all frustrated when trying to learn the C++ equivalent (Vectors).

I'm writing a function that removes a certain int given from a vector of ints. For awhile I could not figure out why it was causing a segmentation fault. After looking at the documentation I realized .erase also removes any element after the one being erased. Which is definitely not what I want to do, so I'm a little lost of how I would go about removing only a single element from a vector without removing the elements after.

Function that I currently have which causes a segmentation fault: 

void remove(int n){

    for(int a=0; a<list.size(); a++){

        if(list.at(a)==n){
            list.erase (list.begin()+(n-1));
            cout << n << " has been erased" << endl;
            break;
        }
    }
}

Upvotes: 1

Views: 4284

Answers (3)

Vlad
Vlad

Reputation: 18633

You're looking for n as an element, but are also using it as an index. I don't think this is what you want.

If you replace (n-1) by a, it should work:

        list.erase(list.begin()+a);

Alternative way to remove a single element, using find and erase:

#include <algorithm>
//...
void removeOne(int n){
    vector<int>::iterator found = std::find(list.begin(), list.end(), n) ;
    if (found!=list.end())
        list.erase(found);
}

Upvotes: 3

Vijay
Vijay

Reputation: 67211

std::vector<int> v; 
// fill it up somehow
v.erase(std::remove(v.begin(), v.end(), 99), v.end()); 
// really remove all elements with value 99

Upvotes: 2

Kris Dunning
Kris Dunning

Reputation: 127

You'll be needing iterator erase ( iterator first, iterator last );

see here. (http://www.cplusplus.com/reference/stl/vector/erase/)

Upvotes: 0

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