STL source code analysis (Hou Jie) notes - STL overview

1、STL The difference with object-oriented

Basically no use of various virtual function , Inheritance, etc , Mainly used templates Made out of

2、STL Six parts

distributor (allocator)、 Containers 、 iterator 、 functor 、 Algorithm 、 Adapter

3、C++ Standard library and STL The relationship between

C++ Standard library >STL,STL It contains six parts ,C++ The standard library also contains some other things

4、STL The relationship between the six components

• Containers ： Containers can let us not pay attention to memory management , Add elements directly into it , Therefore, the container needs the support of the distributor .

• distributor ： Implement memory management of containers .

• Algorithm ： Reflect the relationship with OOP The difference between , And the data section ( Containers ） Separate , The object-oriented idea will put data and functions into classes to contain .

• iterator ： A generalized pointer , Implement operations such as finding containers .

• functor ： The functionality , Realize the addition, addition, subtraction, etc. of objects , Conceptual

• Adapter ： Some parts can be converted , Include container 、 functor 、 Algorithm adapter
  Code case ：
  
  The above figure contains six parts , We can explore allocator How to use .

5、 The iterator is closed before and opened after

For all containers , Its iterator begin() and end() Meaning is closed before opening , namely begin() Point to 0 Elements ,end Point to the next position of the last element .

Container<T> c;
Container<T>::iterator iter = c.begin();
for (; iter != c.end(); ++iter) //  For condition judgment !=,iter++ Until end, That is, traverse all elements 

Above picture ,c.end() The location pointed to is the next location of the memory space of the last element in the container , Non container space .*(c.begin()) To dereference ,*(c.end()) Invalid , because c.end() The memory of the location does not belong to the container itself .