C++ std:.auto_ptr or std::unique_ptr (to support multiple compilers, even old C++03 compilers)?

1. Use boost::unique_ptr:

   #include 
   
   class MyClass {
   private:
     boost::unique_ptr m_ptr;
   };
   

2. Conditionally use auto_ptr or unique_ptr:

   #if __cplusplus < 201103L
   #include 
   #else
   #include 
   #endif
   
   class MyClass {
   private:
   #if __cplusplus < 201103L
     std::auto_ptr m_ptr;
   #else
     std::unique_ptr m_ptr;
   #endif
   };
   

3. Use a preprocessor macro:

   #define AUTO_PTR std::auto_ptr
   
   class MyClass {
   private:
     AUTO_PTR m_ptr;
   };
   

   Note that this macro approach is not recommended, as it can lead to subtle errors if you are not careful.

4. Wrap the std:: smart pointer in your own defined template smart pointer class:

   template 
   class MySmartPtr {
   private:
     std::unique_ptr m_ptr;
   
   public:
     MySmartPtr(T* ptr) : m_ptr(ptr) {}
   
     T* get() { return m_ptr.get(); }
   
     T* release() { return m_ptr.release(); }
   };
   
   class MyClass {
   private:
     MySmartPtr m_ptr;
   };