Wrapper is generally defined as the packaging, or to bound an object.

A "wrapper class" is used to manage the resources so that it will be crystal-clear to every one. This wraps the resources by simply wrapping the pointer into an int. In this another function is called having less code.

The resources are wrapped in a proper manner so that code  will be correct and clean. Wrapper class is also known as Adaptor class.

class int_ptr_wrapper

{

public: 
int_ptr_wrapper(int value = 0) : 
mInt(new int(value)) {} 
// note! needs copy-constructor and copy-assignment operator! 
~int_ptr_wrapper() 
{ 
     delete mInt;
 }
 private:
    int* mInt; 
};

There are two types of wrappers:-

• resource wrappers
• functional wrappers

1. Resource wrappers- 

Functions provided by the OS

• UNIXs: open/close, mmap/munmap, dlopen/dlclose
• Windows: CreateFile/DestroyHandle, CreateFileMapping/CloseHandle, LoadLibrary/FreeLibrary

2. Functional wrappers-

Functions provided by OS

• UNIXs: write, read, dlsym
• Windows: ReadFile, WriteFile, GetProcAddress