应用场景：
在内存中维持一个有序的vector：
1 // VectorSort.cpp : Defines the entry point for the console application.
2
3 #include <iostream>
4 #include <vector>
5 #include <algorithm>
6
7 //先自定义一个结构体
8 struct Test {
9 float member1;
10 std::string member2;
11
12 };
13 bool SortByM1( const Test* v1, const Test* v2)//注意：本函数的参数的类型一定要与vector中元素的类型一致
14 {
15 return v1->member1 > v2->member1; //降序排列
16 //return v1->member1 > v2->member1; //升序排列
17 }
18 void PrintVector( std::vector<Test*> & vec)
19 {
20 /*
21 插一句，
22 vec.begin()对应的位置是向量的第一个位置，
23 vec.end()对应的是vector中的最后的一个元素位置的后面的一个位置（我认为，实际上是一个无效位置）
24 文档上的定义：Returns an iterator referring to the past-the-end element in the vector container.
25 */
26 for(std::vector<Test*>::iterator it = vec.begin() ; it != vec.end() ; it++ )
27 {
28 std::cout<<(*it)->member1<<‘\t‘<<(*it)->member2<<std::endl;
29 }
30 }
31
32 int main(int argc, char* argv[])
33 {
34 std::vector<Test*> vecTest;
35 std::string stt;
36 for(int i=0; i<10;++i){
37 stt = "sh" + stt;
38 Test* tmp = new Test();
39 tmp->member1 = i;
40 tmp->member2 = stt;
41 vecTest.push_back(tmp);
42 }
43
44 //排序之前
45 std::cout<<"Before Sort:"<<std::endl;
46 PrintVector(vecTest);
47
48 std::cout<<"对向量中的所有元素按member1进行升序排列:"<<std::endl;
49 std::sort(vecTest.begin(),vecTest.end(), SortByM1);
50 PrintVector(vecTest);
51
52 //std::cout<<"对向量中的第2个到第5个元素按member1进行升序排列:"<<std::endl;
53 //std::sort(vecTest.begin()+1,vecTest.begin()+5,SortByM1);//vecTest.begin()+5为第6个位置
54 //PrintVector(vecTest);
55
56 for(std::vector<Test*>::iterator it = vecTest.begin();
57 it != vecTest.end(); ++it){
58 delete *it; #free掉内存
59 }
60
61 return 0;
62 }
63
64 [email protected]:~/cp/test# g++ vector_sort.cpp -g -Wall
65 [email protected]:~/cp/test# ./a.out
66 Before Sort:
67 0 sh
68 1 shsh
69 2 shshsh
70 3 shshshsh
71 4 shshshshsh
72 5 shshshshshsh
73 6 shshshshshshsh
74 7 shshshshshshshsh
75 8 shshshshshshshshsh
76 9 shshshshshshshshshsh
77 对向量中的所有元素按member1进行升序排列:
78 9 shshshshshshshshshsh
79 8 shshshshshshshshsh
80 7 shshshshshshshsh
81 6 shshshshshshsh
82 5 shshshshshsh
83 4 shshshshsh
84 3 shshshsh
85 2 shshsh
86 1 shsh
87 0 sh
[email protected]:~/cp/test# valgrind --tool=memcheck --leak-check=yes ./a.out
==24247== Memcheck, a memory error detector
==24247== Copyright (C) 2002-2011, and GNU GPL‘d, by Julian Seward et al.
==24247== Using Valgrind-3.7.0 and LibVEX; rerun with -h for copyright info
==24247== Command: ./a.out
==24247==
Before Sort:
0 sh
1 shsh
2 shshsh
3 shshshsh
4 shshshshsh
5 shshshshshsh
6 shshshshshshsh
7 shshshshshshshsh
8 shshshshshshshshsh
9 shshshshshshshshshsh
对向量中的所有元素按member1进行升序排列:
9 shshshshshshshshshsh
8 shshshshshshshshsh
7 shshshshshshshsh
6 shshshshshshsh
5 shshshshshsh
4 shshshshsh
3 shshshsh
2 shshsh
1 shsh
0 sh
==24247==
==24247== HEAP SUMMARY:
==24247== in use at exit: 0 bytes in 0 blocks
==24247== total heap usage: 25 allocs, 25 frees, 768 bytes allocated
==24247==
==24247== All heap blocks were freed -- no leaks are possible
==24247==
==24247== For counts of detected and suppressed errors, rerun with: -v
==24247== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 2 from 2)