实战c++中的vector系列--使用sort算法对vector进行排序(对vector<string>排序、使用稳定的排序std::stable_sort())

来源：互联网发布：iphone5susb共享网络编辑：程序博客网时间：2024/04/28 08:19

写了挺多关于vector的操作了，正好工作中遇到对vector进行排序的问题，这里就讨论一下。

直接使用sort算法，那就先了解一下：

template <class RandomAccessIterator>  void sort (RandomAccessIterator first, RandomAccessIterator last);template <class RandomAccessIterator, class Compare>  void sort (RandomAccessIterator first, RandomAccessIterator last, Compare comp);

Sorts the elements in the range [first,last) into ascending order.
The elements are compared using operator< for the first version, and comp for the second.
Equivalent elements are not guaranteed to keep their original relative order (see stable_sort).
也就是所说的不稳定排序。

直接上代码：

#include <iostream>     // std::cout#include <algorithm>    // std::sort#include <vector>       // std::vector#include <string>bool myfunction(int i, int j) { return (i<j); }struct myclass {    bool operator() (int i, int j) { return (i<j); }} myobject;int main() {    int myints[] = { 32,71,12,45,26,80,53,33 };    std::vector<int> myvector(myints, myints + 8);// 32 71 12 45 26 80 53 33    // using default comparison (operator <)    std::sort(myvector.begin(), myvector.begin() + 4);  //(12 32 45 71)26 80 53 33    // using function as comp    std::sort(myvector.begin() + 4, myvector.end(), myfunction); // 12 32 45 71(26 33 53 80)    // using object as comp    std::sort(myvector.begin(), myvector.end(), myobject);  //(12 26 32 33 45 53 71 80)    // print out content:    std::cout << "myvector contains:";    for (std::vector<int>::iterator it = myvector.begin(); it != myvector.end(); ++it)        std::cout << ' ' << *it;    std::cout << '\n';    // Sorting the string vector    std::vector<std::string> stringVec = { "John", "Bob", "Joe", "Zack", "Randy" };    sort(stringVec.begin(), stringVec.end());    for (std::string &s : stringVec)        std::cout << s << " ";    return 0;}//输出：myvector contains: 12 26 32 33 45 53 71 80Bob Joe John Randy Zack

这个时候可以使用std::stable_sort()来实现稳定的排序了：
Sorts the elements in the range [first,last) into ascending order, like sort, but stable_sort preserves the relative order of the elements with equivalent values.

#include <iostream>     // std::cout#include <algorithm>    // std::stable_sort#include <vector>       // std::vectorbool compare_as_ints(double i, double j){    return (int(i)<int(j));}int main() {    double mydoubles[] = { 3.14, 1.41, 2.72, 4.67, 1.73, 1.32, 1.62, 2.58 };    std::vector<double> myvector;    myvector.assign(mydoubles, mydoubles + 8);    std::cout << "using default comparison:";    std::stable_sort(myvector.begin(), myvector.end());    for (std::vector<double>::iterator it = myvector.begin(); it != myvector.end(); ++it)        std::cout << ' ' << *it;    std::cout << '\n';    myvector.assign(mydoubles, mydoubles + 8);    std::cout << "using 'compare_as_ints' :";    std::stable_sort(myvector.begin(), myvector.end(), compare_as_ints);    for (std::vector<double>::iterator it = myvector.begin(); it != myvector.end(); ++it)        std::cout << ' ' << *it;    std::cout << '\n';    return 0;}//输出：using default comparison: 1.32 1.41 1.62 1.73 2.58 2.72 3.14 4.67using 'compare_as_ints' : 1.41 1.73 1.32 1.62 2.72 2.58 3.14 4.67

2 0