c++ list sort

  1.    bool operator < (S & b) {return ID < b.ID;}

struct S {std::string firstname;std::string secondname;int ID;bool operator < (S & b) {return ID < b.ID;}// 重新定义小于，因为默认的sort函数调用的操作符是<，所以我们只需要重载 < 就好了
};int main(int argc, char* argv[])
{std::list<S> mylist;std::list<S>::iterator iter;S a;a.firstname ="dfadf";a.ID = 5;mylist.push_back (a);a.firstname ="得到";a.ID = 9;mylist.push_back (a);a.firstname ="xxx";a.ID = 7;mylist.push_back (a);a.firstname ="gggg";a.ID = 25;mylist.push_back (a);mylist.sort();

2.

#include "stdafx.h"
#include <iostream> 
#include <list>
using namespace std;class A{
public:A(int m):a(m){}bool operator <(const A& other){<span style="font-size: 18px;">    return a < other.a;</span>}friend std::ostream& operator <<(std::ostream& out, const A& obj){out<< obj.a<<endl;return out;}
private:int a;
};int _tmain(int argc, _TCHAR* argv[])
{  list<A> S;typedef list<A>::iterator it;S.push_back(A(3));S.push_back(A(2));S.push_back(A(5));S.sort();it it1 = S.begin();it it2 = S.end();while(it1 != it2){cout<<*it1<<endl;it1++;}return 0;
}

3.

// list_sort.cpp
// compile with: /EHsc
#include <list>
#include <iostream>
 
int main( )
{
   using namespace std;
   list <int> c1;
   list <int>::iterator c1_Iter;
    
   c1.push_back( 20 );
   c1.push_back( 10 );
   c1.push_back( 30 );
 
   cout << "Before sorting: c1 =";
   for ( c1_Iter = c1.begin( ); c1_Iter != c1.end( ); c1_Iter++ )
      cout << " " << *c1_Iter;
   cout << endl;
 
   c1.sort( );
   cout << "After sorting c1 =";
   for ( c1_Iter = c1.begin( ); c1_Iter != c1.end( ); c1_Iter++ )
      cout << " " << *c1_Iter;
   cout << endl;
 
   c1.sort( greater<int>( ) );
   cout << "After sorting with 'greater than' operation, c1 =";
   for ( c1_Iter = c1.begin( ); c1_Iter != c1.end( ); c1_Iter++ )
      cout << " " << *c1_Iter;
   cout << endl;
}