c++ 嵌套类

// ConsoleApplication7.cpp : 此文件包含 "main" 函数。程序执行将在此处开始并结束。
//

#include <iostream>
#include<string>
#include<vector>
#include<functional>
using namespace std;
using namespace placeholders;


class TextQuery
{
public:
	class QueryResult;

	QueryResult query(const string& s)const;
};




class TextQuery::QueryResult
{
	friend std::ostream& print(std::ostream&, const QueryResult&);
public:
	QueryResult(const std::string& s): a(s){}

	static string member;


	string a;


};
// this is very important to define this method after class QueryResult //get its body 
TextQuery::QueryResult
TextQuery::query(const string& s)const
{
	return TextQuery::QueryResult(s);
}


std::ostream&
print(std::ostream& os, const TextQuery::QueryResult& s)
{
	return os << s.a;
}




string TextQuery::QueryResult::member = "SoS";


 

int main(int argn, char** args)
{
 
	TextQuery q;
	auto a  = q.query("xiaozhang");
	print(cout,a);
 
	return 0;
}