STL tutorial 10 container commonalities and usage scenarios

Generality

• except queue And stack These two special containers with limited access , Each container provides functions that return iterators , Using the returned iterator, you can access the element .
• Usually STL No exceptions will be thrown . Ask the user to ensure that the correct parameters are passed .
• Each container provides a default constructor and a default copy constructor .
• Size dependent construction method ：1 size() Returns the number of elements in the container 2empty() Judge whether the container is empty

STL Container use timing

1）vector Use scenarios

For example, the storage of software history operation records , Historical record , Last record

2）deque Use scenarios

First in first out scenario , For example, the queuing system , The storage of the queue can adopt deque, Supports fast removal of headers , Quick addition of tail . If the vector, When the head end is removed , It moves a lot of data , Slow speed .

vector and deque Compare

• vector.at() Than deque.at() Efficient , such as vector.at(0) Is constant ,deque The starting position of is not fixed .
• If there are a lot of release operations ,vector It takes less time , This is related to the internal implementation of both .
• deque Support quick insertion and removal of head , This is a deque The advantages of .

3）list Use scenarios

For example, the storage of bus passengers , Passengers may get off at any time , Support frequent removal and insertion of elements with uncertain positions

4）set Use scenarios

For example, the storage of personal score records of mobile games , The storage requirements are arranged from high score to low score .

5）map Use scenarios

For example, press ID Number stores 100000 users , If you want to be fast, you have to pass ID Find the corresponding user . Search efficiency of binary tree , This is reflected . If it is vector Containers , In the worst case, you may have to traverse the entire container to find the user .