C / C++ / MFC

<span style="color: green;">
/**
 * A test function. Remember that you can't invoke this when the parent dll is loading, because
 * the system will synchronize LoadLibrary(), and this would cause a deadlock in your application.
 */
</span>
<span style="color: blue">void</span> DllTest()
{
   <span style="color: green;">
   // This is the handle to the dll.
   </span>
   HMODULE      hDll;<br> <br>

   <span style="color: green;">
   // This is the pointer to the function in the dll, remember that all functions actually are
   // constant pointers to blocks in memory where code can be found.
   </span>
   <span style="color: blue">void</span> (* pPointerToFunctionInDll) (<span style="color: blue">char</span> * message);<br> <br>

   <span style="color: green;">
   // This call to LoadLibrary will make the system try to locate a dll with the given name.
   // If it finds the dll, it will load it into the process memory space.
   </span>
   hDll = LoadLibrary("test.dll");
   
   <span style="color: blue">if</span> (hDll)
   {
      <span style="color: green;">
      // The call to GetProcAddress, will try to find the exported function with the given
      // name. The return value must of course be cast to match the signature of receiving
      // function pointer.
      </span>
      pPointerToFunctionInDll = (<span style="color: blue">void</span> (*) (<span style="color: blue">char</span> *)) GetProcAddress(hDll, <span style="color: red">"ShowMessage"</span>);

      <span style="color: blue">if</span> (pPointerToFunctionInDll)
      {
         pPointerToFunctionInDll("Hello World!");
      }

      <span style="color: green;">
      // When you're done using your dll, you must unload it from the process space.
      </span>
      FreeLibrary(hDll);
   }
}