vector 自定义排序

#include <iostream>
#include <vector>
using std::vector;
struct MyStruct
{
    int key;
    std::string stringValue;

    MyStruct(int k, const std::string& s) : key(k), stringValue(s) {}
};

struct less_than_key
{
    inline bool operator() (const MyStruct& struct1, const MyStruct& struct2)
    {
        return (struct1.key < struct2.key);
    }
};


int main(void)
{

std::vector < MyStruct > vec;

vec.push_back(MyStruct(1, "----"));
vec.push_back(MyStruct(4, "test"));
vec.push_back(MyStruct(3, "a"));
vec.push_back(MyStruct(1, "t"));
vec.push_back(MyStruct(2, "is"));
vec.push_back(MyStruct(1, "th--------is"));

sort(vec.begin(), vec.end(), less_than_key());
for(vector< MyStruct >::iterator cit = vec.begin() ;  cit != vec.end() ; ++cit){
std::cout << cit->key << ":" << cit->stringValue << std::endl;
}

    return 0;
}