Adding __decspec for Windows builds

include/C_Callback.h

@@ -1,27 +1,35 @@
 #ifndef CALLBACK_DEMO_H
 #define CALLBACK_DEMO_H
 
+#ifdef _WIN32
+#define DLL_EXPORT __declspec(dllexport)
+#else
+#define DLL_EXPORT
+#endif
+
+DLL_EXPORT void YourFunction();  // Example function declaration
+
 #ifdef __cplusplus
 extern "C" {
 #endif
 
 typedef const void (*CallbackFunction)(int, char*, size_t);
 
 // Simple function that prints a number to the console
-void printNumberInDec(int number, char* buffer, size_t bufferSize);
+DLL_EXPORT void printNumberInDec(int number, char* buffer, size_t bufferSize);
 
 // Simple function that prints a number to the console in hex
-void printNumberInHex(int number, char* buffer, size_t bufferSize);
+DLL_EXPORT void printNumberInHex(int number, char* buffer, size_t bufferSize);
 
 // Function that takes a function pointer as an argument and
 // set the callback function to the one passed in
-void setCallback(CallbackFunction callback);
+DLL_EXPORT void setCallback(CallbackFunction callback);
 
 // Run the callback function with the given number
-void runCallback(int number, char* buffer, size_t bufferSize);
+DLL_EXPORT void runCallback(int number, char* buffer, size_t bufferSize);
 
 #ifdef __cplusplus
 } 
 #endif
 
-#endif // CALLBACK_DEMO_H
+#endif // CALLBACK_DEMO_H