STL之使用vector排序

应用场景：

　　在内存中维持一个有序的vector：

 // VectorSort.cpp : Defines the entry point for the console application.

 #include <iostream>
 #include <vector>
 #include <algorithm>

 //先自定义一个结构体
 struct Test {
     float member1;
     std::string member2;

 };
 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
 {
     return v1->member1 > v2->member1;       //降序排列
     //return v1->member1 > v2->member1;     //升序排列
 }
 void PrintVector( std::vector<Test*> & vec)
 {
     /*
         插一句，
         vec.begin()对应的位置是向量的第一个位置，
         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）
         文档上的定义：Returns an iterator referring to the past-the-end element in the vector container.
     */
     for(std::vector<Test*>::iterator it = vec.begin() ; it != vec.end() ; it++ )
     {
         std::cout<<(*it)->member1<<'\t'<<(*it)->member2<<std::endl;
     }
 }

 int main(int argc, char* argv[])
 {
     std::vector<Test*> vecTest;
     std::string stt;
     for(int i=; i<;++i){
         stt = "sh" + stt;
         Test* tmp = new Test();
         tmp->member1 = i;
         tmp->member2 = stt;
         vecTest.push_back(tmp);
     }

     //排序之前
     std::cout<<"Before Sort:"<<std::endl;
     PrintVector(vecTest);

     std::cout<<"对向量中的所有元素按member1进行升序排列:"<<std::endl;
     std::sort(vecTest.begin(),vecTest.end(), SortByM1);
     PrintVector(vecTest);

     //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;
     //std::sort(vecTest.begin()+1,vecTest.begin()+5,SortByM1);//vecTest.begin()+5为第6个位置
     //PrintVector(vecTest);

     for(std::vector<Test*>::iterator it = vecTest.begin();
         it != vecTest.end(); ++it){
         delete *it;          #free掉内存
     }

     return ;
 }

 root@u18:~/cp/test# g++ vector_sort.cpp  -g -Wall
 root@u18:~/cp/test# ./a.out
 Before Sort:
     sh
     shsh
     shshsh
     shshshsh
     shshshshsh
     shshshshshsh
     shshshshshshsh
     shshshshshshshsh
     shshshshshshshshsh
     shshshshshshshshshsh
 对向量中的所有元素按member1进行升序排列:
     shshshshshshshshshsh
     shshshshshshshshsh
     shshshshshshshsh
     shshshshshshsh
     shshshshshsh
     shshshshsh
     shshshsh
     shshsh
     shsh
     sh    

root@u18:~/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)