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copied!<p>If you are using C.99, you can use a variable length array (VLA) to dynamically allocate your 3-dimensional array. Once <code>side</code> is determined, you can declare your pointer to be:</p> <pre><code>char (*cube3d_)[side][side]; </code></pre> <p>And then initialize it like this:</p> <pre><code>cube3d_ = malloc(side * sizeof(*cube3d_)); </code></pre> <p>Note that in C, you are not required to cast the return value of <code>malloc()</code>, and doing so can actually lead to undefined behavior in the worst case. Since the "cube" has been allocated as a contiguous block, it can be copied with <code>memcpy()</code>.</p> <p>C++ does not have VLA. You can use a <code>vector</code> to get the C++ equivalent of your multi-dynamic allocation structure:</p> <pre><code>std::vector<std::vector<std::vector<char> > > cube3d_(side, std::vector<std::vector<char> >(side, std::vector<char>(side))); </code></pre> <p>You can then copy it using a copy constructor or an assignment.</p> <hr> <p>If <code>cube3d_</code> is a member variable of an object/structure, so long as your object knows the value of <code>side</code>, you can still use a VLA pointer to access the memory. For example:</p> <pre><code>struct Obj { size_t side_; void *cube3d_; }; //... size_t side = 3; //... Obj o; o.side_ = side; char (*p)[o.side_][o.side_] = malloc(o.side_ * sizeof(*p)); o.cube3d_ = p; //... char (*q)[o.side_][o.side_] = o.cube3d_; q[1][2][2] = 'a'; </code></pre>

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