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copied!<p>With gcc 4.3.4, using switches -O2 -Wstrict-aliasing, dreamlax's answer will produce:</p> <pre><code>warning: dereferencing type-punned pointer will break strict-aliasing rules </code></pre> <p><strong>Added:</strong> I think the objections to caf's answer about <strong><em>endianness</em></strong> and size are reasonable, which his solution does not address (no pun intended). Dustin's suggestion for using a union cast is probably legal (although from what I read there seems to be some debate, but <em>your</em> compiler does is important than the law). But his code could be simplified (or obfuscated, depending on your taste) by the one-liner:</p> <pre><code>printf("%p\n", ((union {int (*from)(void); void *to;})funcptr).to); </code></pre> <p>This removes the gcc strict-aliasing warning (but is it 'correct'?).</p> <p>Aggregate casts won't 'work' if you are using the -pedantic switch, or are using e.g. SGI IRIX, so you'll need to use:</p> <pre><code>printf("%p\n", ((union {int (*from)(void); void *to;} *)&funcptr)->to); </code></pre> <p>But regarding the original question: its origin lies in the use of -pedantic, which I think is slightly pedantic :).</p> <p><strong>Further edit:</strong> Note you cannot use <strong>main</strong> in the last example, as in:</p> <pre><code>printf("%p\n", ((union {int (*from)(void); void *to;}) main).to); // ok printf("%p\n", ((union {int (*from)(void); void *to;} *)&main)->to); // wrong! </code></pre> <p>because of course <strong>&main</strong> decays to <strong>main</strong>.</p>

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