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copied!<p>Your first problem is related to the way arrays are (not) handled in C++. Arrays live a kind of very fragile shadow existence where, if you as much as look at them in a funny way, they are converted into pointers. Your function doesn't take two pointers-to-arrays as you expect. It takes two pointers to pointers.</p> <p>In other words, you lose all information about the <em>size</em> of the arrays. <code>sizeof(a)</code> doesn't give you the size of the array. It gives you the size of a pointer to a pointer.</p> <p>So you have two options: the quick and dirty ad-hoc solution is to pass the array sizes explicitly:</p> <pre><code>gboolean foo (gchar** a, int a_size, gchar** b, int b_size) </code></pre> <p>Alternatively, and much nicer, you can use vectors instead of arrays:</p> <pre><code>gboolean foo (const std::vector<gchar*>& a, const std::vector<gchar*>& b) </code></pre> <p>Vectors are dynamically sized arrays, and as such, they know their size. <code>a.size()</code> will give you the number of elements in a vector. But they also have two convenient member functions, <code>begin()</code> and <code>end()</code>, designed to work with the standard library algorithms.</p> <p>So, to sort a vector:</p> <pre><code>std::sort(a.begin(), a.end()); </code></pre> <p>And likewise for <code>std::includes</code>.</p> <p>Your <em>second</em> problem is that you don't operate on strings, but on char pointers. In other words, <code>std::sort</code> will sort by pointer address, rather than by string contents.</p> <p>Again, you have two options:</p> <p>If you insist on using char pointers instead of strings, you can specify a custom comparer for <code>std::sort</code> (using a lambda because you mentioned you were ok with them in a comment)</p> <pre><code>std::sort(a.begin(), a.end(), [](gchar* lhs, gchar* rhs) { return strcmp(lhs, rhs) < 0; }); </code></pre> <p>Likewise, <code>std::includes</code> takes an optional fifth parameter used to compare elements. The same lambda could be used there.</p> <p>Alternatively, you simply use <code>std::string</code> instead of your char pointers. Then the default comparer works:</p> <pre><code>gboolean foo (const std::vector<std::string>& a, const std::vector<std::string>& b) { gboolean result; std::sort (a.begin(), a.end()); std::sort (b.begin(), b.end()); result = std::includes (b.begin(), b.end(), a.begin(), a.end()); return result; } </code></pre> <p>Simpler, cleaner and safer.</p>

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