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    <p>The first problem is that you use the nested class <code>graph::vertex</code> before declaring it. Further confusion is caused because you've declared <code>class vertex</code> <em>outside</em> <code>graph</code>, so the compiler initially thinks you mean that class. You could declare <code>vertex</code> near the start of <code>graph</code>:</p> <pre><code>template &lt;class T&gt; class graph { class vertex; private: // and so on }; </code></pre> <p>There are several other syntax errors, which should be obvious if you look at the lines referred to by the error messages. The syntax for a range-based for loop is</p> <pre><code>for (auto v : verts) // not for each(auto v in verts) </code></pre> <p>This gives you key-value pairs, so to delete the <code>vertex</code>, you need</p> <pre><code>delete v.second; </code></pre> <p>Better still, change <code>verts</code> into <code>unordered_map&lt;T, vertex&gt;</code>, containing objects rather than pointers, and it will manage all its memory automatically - you won't need a destructor at all.</p> <p>The syntax for a value-initialised temporary is</p> <pre><code>T() // not default(T) </code></pre> <p>Clauses in a constructor's initialiser list are separated by commas, not colons:</p> <pre><code>path(vertex *d = nullptr, double c = 0.0) : dest(d) , cost(c) {} ^ not : </code></pre> <p>A <code>double</code> with infinite value is</p> <pre><code>std::numeric_limits&lt;double&gt;::infinity() // not double.infinity() </code></pre> <p>for which you need to in include <code>&lt;limits&gt;</code>.</p> <p><code>verts</code> doesn't need deleting in the destructor, since you don't <code>new</code> it. Nor does it need assigning from a default-constructed temporary in the constructor, since it's just been default-constructed.</p> <p>There are a few places where you are making life difficult for yourself through unnecessary use of pointers and <code>new</code>. Try to avoid <code>new</code> except when you really need it; and learn about <a href="http://en.wikipedia.org/wiki/Resource_Acquisition_Is_Initialization" rel="nofollow">RAII</a>, especially the use of smart pointers and containers, for when you do.</p>
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    1. USMike Seymour
    1. USMike Seymour
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    1. COWow, Thanks. I'm going to scrap this code and do it again tomorrow with this feedback. I've had enough poking around trying to get it to work. But a lot of those things you point out weren't even coming up as error messages when I try compile that class as a whole. (MS C++) Unless I force it into main as a little test snippet and sometimes not even then. For example that incorrect for each syntax compiles and behaves as expected. I am downloading clang on this new computer, but since I live in a rural area the download is taking a little while.
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    2. CO@MorphingDragon: Since it's a template, a lot of the errors won't be detected unless the function or class they're in is instantiated - which won't (usually) happen unless the program uses it. Try building up large classes by adding a small bit of functionality at a time, writing tests as you go, so you don't end up with a huge pile of errors to trawl through.
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