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POc++ implement virtual class defined outside dll,in dll
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  1. POc++ implement virtual class defined outside dll,in dll
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    copied!<p>How can you do this in Windows VS2010?</p> <p>2 projects under the same solution: the first one is a regular console application with two files: s.h, and j.cpp. The second project is a dll application with one header file: j.h</p> <p>s.h:</p> <pre><code>#ifndef M #define M class MyMathFuncs { public: // Returns a + b virtual double Add(double a, double b) const = 0; // Returns a - b virtual double Subtract(double a, double b) const = 0; // Returns a * b virtual double Multiply(double a, double b) const = 0; // Returns a / b // Throws const std::invalid_argument&amp; if b is 0 virtual double Divide(double a, double b) const = 0; }; double MyMathFuncs::Add(double a, double b) const{}; // Returns a - b double MyMathFuncs::Subtract(double a, double b) const{}; // Returns a * b double MyMathFuncs::Multiply(double a, double b) const{}; // Returns a / b // Throws const std::invalid_argument&amp; if b is 0 double MyMathFuncs::Divide(double a, double b) const{}; </code></pre> <p>j.cpp:</p> <pre><code>#include "s.h" #include "j.h" #include &lt;iostream&gt; using namespace std; int main() { double a = 7.4; int b = 99; MyMathFuncs2 k; cout &lt;&lt; "a + b = " &lt;&lt; k.Add(a, b) &lt;&lt; endl; cout &lt;&lt; "a - b = " &lt;&lt; k.Subtract(a, b) &lt;&lt; endl; cout &lt;&lt; "a * b = " &lt;&lt; k.Multiply(a, b) &lt;&lt; endl; cout &lt;&lt; "a / b = " &lt;&lt; k.Divide(a, b) &lt;&lt; endl; try { cout &lt;&lt; "a / 0 = " &lt;&lt; k.Divide(a, 0) &lt;&lt; endl; } catch (const invalid_argument &amp;e) { cout &lt;&lt; "Caught exception: " &lt;&lt; e.what() &lt;&lt; endl; } char c; cin &gt;&gt; c; return 0; } </code></pre> <p>in dll, j.h:</p> <pre><code>#ifndef dllheader #define dllheader #include "s.h" #include &lt;stdexcept&gt; class MyMathFuncs2: public MyMathFuncs { public: __declspec(dllexport) double Add(double a, double b) const { return a + b; } // Returns a - b __declspec(dllexport) double Subtract(double a, double b) const { return a - b; } // Returns a * b __declspec(dllexport) double Multiply(double a, double b) const { return a * b * b * b; } // Returns a / b // Throws const std::invalid_argument&amp; if b is 0 __declspec(dllexport) double Divide(double a, double b) const { if (b == 0) { //throw invalid_argument("b cannot be zero!"); } return a / b; } } #endif </code></pre> <p>The dll compiles but the console app does not:</p> <pre><code>files (x86)\microsoft visual studio 10.0\vc\include\typeinfo(36): error C2236: unexpected 'struct' '__type_info_node'. Did you forget a ';'? 1&gt;c:\program files (x86)\microsoft visual studio 10.0\vc\include\typeinfo(36): error C2143: syntax error : missing ';' before '{' 1&gt;c:\program files (x86)\microsoft visual studio 10.0\vc\include\typeinfo(36): error C2447: '{' : missing function header (old-style formal list?) 1&gt;c:\program files (x86)\microsoft visual studio 10.0\vc\include\typeinfo(41): error C2146: syntax error : missing ';' before identifier '__type_info_root_node' 1&gt;c:\program files (x86)\microsoft visual studio 10.0\vc\include\typeinfo(41): error C4430: missing type specifier - int assumed. Note: C++ does not support default-int 1&gt;c:\program files (x86)\microsoft visual studio 10.0\vc\include\typeinfo(41): error C4430: missing type specifier - int assumed. Note: C++ does not support default-int 1&gt;c:\program files (x86)\microsoft visual studio 10.0\vc\include\typeinfo(67): error C2061: syntax error : identifier '__type_info_node' 1&gt;c:\program files (x86)\microsoft visual studio 10.0\vc\include\typeinfo(74): error C2061: syntax error : ide </code></pre>
 

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