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POHeaders Including Each Other in C++
 

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    <p>I'm a C++ newbie, but I wasn't able to find the answer to this (most likely trivial) question online. I am having some trouble compiling some code where two classes include each other. To begin, should my #include statements go inside or outside of my macros? In practice, this hasn't seemed to matter. However, in this particular case, I am having trouble. Putting the #include statements outside of the macros causes the compiler to recurse and gives me "#include nested too deeply" errors. This seems to makes sense to me since neither class has been fully defined before #include has been invoked. However, strangely, when I try to put them inside, I am unable to declare a type of one of the classes, for it is not recognized. Here is, in essence, what I'm trying to compile:</p> <p>A.h</p> <pre><code>#ifndef A_H_ #define A_H_ #include "B.h" class A { private: B b; public: A() : b(*this) {} }; #endif /*A_H_*/ </code></pre> <p>B.h</p> <pre><code>#ifndef B_H_ #define B_H_ #include "A.h" class B { private: A&amp; a; public: B(A&amp; a) : a(a) {} }; #endif /*B_H_*/ </code></pre> <p>main.cpp</p> <pre><code>#include "A.h" int main() { A a; } </code></pre> <p>If it makes a difference, I am using g++ 4.3.2.</p> <p>And just to be clear, in general, where should #include statements go? I have always seen them go outside of the macros, but the scenario I described clearly seems to break this principle. Thanks to any helpers in advance! Please allow me to clarify my intent if I have made any silly mistakes!</p>
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