Auto and decltype

What problem to solve

The main purpose of generic programming is to solve the problem that some types are difficult to represent by template parameters

Auto in the compiler deduces the type of the variable from the type to the right of =
Decltype Specifies the type of the expression derived by the compiler
Auto and decltype are used together to derive the type of the return value of a function

Template <typename T, typename U> //return_value add(T T, U U) {return T + U; Auto add(T T, U U) -> decltype(T + U) {return T + U; }Copy the code

Use RAII(resource fetch as initialization) to solve memory problems caused by coding such as memory leaks, double free, etc

C++ 11 introduces three types of smart Pointers:

STD ::shared_ptr Multiple objects simultaneously point to the same memory
STD :: Weak_ptr acts as a bystander to monitor the existence of managed resources in shareD_Ptr and solve the circular reference problem
STD ::unique_ptr An object occupies a chunk of memory