zoukankan      html  css  js  c++  java
  • the philosophy behind of the design of the STL

    The concept of STL is based on a separation of data and operations. The data is managed by container classes, and the operations are defined by configurable algorithms. Iterators are the glue between these two components and they let any algorithm interact with any container.

     

    //violate using the iterator as the glue between the containers and the algorithm 
    template<T>
    Print(List<T> & container)
    {
        for(T item: container)
         {
            //...
         }
    }
     
    //correct
    template<T>
    Print(iterator<T> begin, iterator<T> end)
    {
        for(;begin < end && begin != end; begin ++)
        {
            //...
        }
    }
    1. The STL concept contradicts the original idea of object-oriented programming: the STL serarates data and algorithms rather than combining them. While you can combine every kinds of container with ever kind of algorithm, so the result is a very flexible but still rather small framework.
    2. The particular implementation of any container is not defined by the C++ standard library. However, the behavior and complexity secified by the standard do not leave much room for variation.
    3. The STL containers provide only those special member functions that in general have "good" performance, where "good" normal means constant or logarithmic complexity. e.g., a direct element access by using operator [] is not provided for lists. This is because lists don't provide random access, and so an operator [] would have bad performance. Which is also most like why there is no resize() for array. 
  • 相关阅读:
    二分查找算法
    http协议。会话控制cookie、session
    154. Find Minimum in Rotated Sorted Array II
    8. String to Integer (atoi)
    528. Random Pick with Weight
    415. Add Strings
    158. Read N Characters Given Read4 II
    157. Read N Characters Given Read4
    19. Remove Nth Node From End of List
    29. Divide Two Integers
  • 原文地址:https://www.cnblogs.com/Cmpl/p/3747328.html
Copyright © 2011-2022 走看看