Pointers in C.

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Best documents for Pointers in C.
This document will make life easier for those who thinks "Pointer: A difficult Topic". 

https://docs.google.com/file/d/0Bz7eXe9Jx0skOWFkTW1CS2lEUWs/preview

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C++ Guidelines for Multithreaded System

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Mutithreading è Parallelism è  Achieve concurrency. Below are some of the guidelines to follow for building C++ Multithreaded system. Ø std::thread function arguments are pass by value by default. Thread function arguments are pass by value by default. So, if you want the change to be persisted in the arguments passed in , then pass them by reference using std::ref(). Ø Protect shared data or resource using critical section.     In a multithreaded environment if there are more than one thread sharing the resource/data then often it results in a undefined behaviour if the resource/shared data is not protected using synchronise mechanism. So, the shared resource/data must be protected with std::mutex . Ø Release lock after critical section. If a thread T1 acquires lock (mutex.lock()) before entering critical section and forgets to unlock(mutex.unlock()) then all the other threads will be blocked indefinitely and the program might hang because thre...
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std::weak_ptr

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std::weak_ptr std::weak_ptr is'nt a standalone smart pointer. It's an augmentation of std::shared_ptr.  It do not contribute to the reference count of the managed object they refer to. By using just the raw pointer, it is impossible to know if the referenced data has been deallocated or not. std::weak_ptr provides a "expired" API to check if the shared_ptr it was pointing to is expired. In a nutshell - The weak_ptr class template stores a “weak reference” to an object that’s already managed by a shared_ptr . To access the object, a weak_ptr can be converted to a shared_ptr using the shared_ptr constructor or the member function lock. When the last shared_ptr to the object goes away and the object is deleted, the attempt to obtain a shared_ptr from the weak_ptr instances that refer to the deleted object will fail: the constructor will throw an exception of type boost::bad_weak_ptr, and weak_ptr::lock will return an empty shared_ptr . auto...
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std::shared_ptr

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std::shared_ptr  for shared ownership An object accessed via std::shared_ptr s has its lifetime managed by those pointers through shared ownership. No specific std::shared_ptr owns the object. Instead all shared_ptr’s pointing to it collaborates to ensure its destruction at the point where it’s no longer needed. When the last shared_ptr pointing to an object stops pointing there, that shared_ptr destroys the object it points to. A shared_ptr can tell whether it’s the last one pointing to a resource by consulting the resource’s reference count, a value associated with the resource that keeps track of how many shared_ptrs point to it. Shared_ptrs constructors increments this count shared_ptr s destructors decrements it and copy assignment operators do both. If sp1 and sp2 are shared_ptr s to different objects, the assignment “ sp1=sp2 ” , modifies sp1 such that it points  to the object pointed to by sp2 . sp1 reference count is decremented, while that for the obj...
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