Does `Vector::erase()` Automatically Destroy Object Pointers?

Does Vector::erase() Destroy Object Pointers?

When working with a vector of object pointers, it's crucial to understand the behavior of vector::erase() on the stored objects. This article explores the issue and provides solutions for maintaining object integrity.

Vector::erase() removes an element from a vector by calling its destructor. If the contained object is a raw pointer, vector::erase() does not take ownership of destroying the referenced object.

To explicitly destroy the referenced objects in a vector of pointers, you must manually call delete on each contained pointer. For instance, the following code snippet demonstrates how to clear the contents of a vector of pointers:

<code class="cpp">void clearVectorContents( std::vector <YourClass*> &amp; a ) {
    for ( int i = 0; i < a.size(); i++ ) {
        delete a[i];
    }

    a.clear();
}

However, storing raw pointers in standard containers is not advisable. A more robust solution is to use shared pointers (e.g., boost::shared_ptr) to ensure proper object destruction.

An Elegant Solution Using Functors and Templates

A generic and elegant alternative is to employ functors and templates for deleting pointers in a vector. Here's a comprehensive example:

<code class="cpp">class DeleteVector {
public:
    bool operator()(T x) const {
        // Delete pointer.
        delete x;
        return true;
    }
};

This functor can be used in conjunction with std::for_each() to iterate through a vector and delete the contained pointers. For example, the following code demonstrates how to use the DeleteVector functor to delete the contents of a vector of myclass pointers:

<code class="cpp">for_each( myclassVector.begin(),myclassVector.end(),
          DeleteVector<myclass*>());</code>

By utilizing this approach, you can seamlessly delete the referenced objects in a vector without worrying about object lifecycle management or potential memory leaks.

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