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POCalling some functions before main in C
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copied!<p>I'd like to do some stuffs before <code>main</code> function. I have multiple source files. In each file, there is some work that needs to be done before <code>main</code>. It was no problem in C++, but problematic with C.</p> <p>In C++, this can be done by two ways:</p> <ol> <li>Exploiting a constructor of a global class/struct.</li> <li>Calling a function to a global variable</li> </ol> <p>For example, <code>static const int __register_dummy_ = __AddRegisterMetaInfo(...);</code></p> <p>However, in C, either ways is impossible. Obviously, there is no constructor. So, the first option is inherently impossible.</p> <p>I thought that the second option would be possible, but not compiled in C (I tested only with Visual C++. It gives <a href="http://msdn.microsoft.com/en-us/library/t801az8a%28v=vs.80%29.aspx" rel="nofollow">C2099</a>.). C only allows a constant to a non-automatic variable. </p> <p>Is there any way to call some functions before main?</p> <hr> <p><strong>EDIT</strong>: It seems that many people just got misunderstand what I really wanted to do. Sorry for writing this question in a simplified way.</p> <p>What I needed to do is implementing a sort of C++ runtime class information feature, just like <a href="http://msdn.microsoft.com/en-us/library/t91eb9y9%28v=vs.80%29.aspx" rel="nofollow">MFC's approach</a>. In this approach, I need to get some information from all source code. For example, say each source file has a definition of a class, and I'd like to see all information (e.g., class names and the parent class). The easiest way is placing a static constructor in each file, and each constructor accesses a global data structure and register its information. But, I also wanted to find a way to implement a similar thing in C. So, simply calling a <code>pre_main_job</code> in <code>main</code> can't be an answer to me.</p> <p>Note that this abuse of static constructor also can be found in LLVM compiler suite. Each optimization/analysis feature is implemented as a pass. All these passes are registered via a static constructor.</p>

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