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    <p>I will reply because predecessors answered only to the question from topic while you are asking more questions and I will also give some advice. In the remainder of this post we will assume that if <code>Points</code> do allocate any dynamic memory, the memory is returned properly when <code>Points</code> are deleted.</p> <blockquote> <p>Class Points has only two instance vars that are all ints but the number of points will only be known when I read this in from the file, so I guess I have to make Points dynamically with new which means I have to destroy them later.</p> </blockquote> <p>This comes with contradiction to what you actually do here</p> <pre><code>class Grid{ public: // initialize vector with 3 points with val 0. Grid(vector&lt;Points&gt; v) : vector&lt;Points&gt;(3, 0) {}; // is this right private: vector&lt;Points&gt; v_points; }; </code></pre> <p>because you create vector without <code>new</code>. However this might be OK if we assume that you first get number of <code>Points</code> and then you are about to create a Grid. <code>std::vector</code> is not C array and might be easily resized, assigned and gives much more flexibility. You do not have to create it on heap because you are afraid about size: vector elements are <a href="https://stackoverflow.com/a/8036528/1141471">always</a> created on heap, it is just a vector itself that is (if it is) on stack. And this is often exactly what we want (see i.e. <a href="http://en.wikipedia.org/wiki/Resource_Acquisition_Is_Initialization" rel="nofollow noreferrer">RAII</a>). The proper way to initialize a vector would be then</p> <pre><code>class Grid{ public: // initialize vector with 3 Points with val Points(0) Grid(vector&lt;Points&gt; v) : v_points(3, Points(0)) {}; private: vector&lt;Points&gt; v_points; }; </code></pre> <p>Note, we do it in initialization list. For POD class members, it makes no difference, it's just a matter of style. For class members which are classes, then it avoids an unnecessary call to a default constructor.</p> <blockquote> <p>Did I initialize constructor correctly and When writing a destructor for Grid do I need to write a destructor for vector like this: ~vecotr() or with delete or using iterator?</p> </blockquote> <p>You don't initialize constructor, rather in constructor initializer list you initialize class members. Since vector is not allocated with <code>new</code>, you will not <code>delete</code> it (call <code>delete</code>). It will be destroyed automatically when <code>Grid</code> is destroyed.</p>
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    1. PODo I need to delete a vector?
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