C++学习笔记（三十）：c++ 多个返回值

返回结构体

#include <iostream>

struct TestResult {
	std::string s1;
	std::string s2;
	int a;
};

TestResult GetStringMessage()
{
	TestResult tr;
	tr.s1 = "Hello ";
	tr.s2 = "pcop!";
	tr.a = 7;
	return tr;
}

int main()
{
	TestResult tr = GetStringMessage();
	std::cout << tr.s1 << tr.s2 << tr.a << std::endl;

	std::cin.get();
	return 0;
}

在方法的参数中传入接收返回值的变量。这样做的弊端是当要返回的参数太多时，方法的参数将会有很多。

#include <iostream>

void GetStringMessage(std::string& s1Out, std::string& s2Out)
{
	s1Out = "Pcop!";
	s2Out = "NIUbi!";
}

int main()
{
	std::string s1,s2;
	GetStringMessage(s1, s2);
	std::cout << s1 << std::endl;
	std::cout << s2 << std::endl;

	std::cin.get();
	return 0;
}

通过返回tuple或者pair来返回多个返回值，tuple或者pair在取值的时候相对比较麻烦，而且可读性比较差。

#include <iostream>
#include <utility>
#include <functional>

std::tuple<std::string, std::string> GetStringMessage()
{
	std::string s1Out = "Pcop!";
	std::string s2Out = "NIUbi!";
	return std::make_tuple(s1Out, s2Out);
}

int main()
{
	std::string s1 = std::get<0>(GetStringMessage()); 
	std::string s2 = std::get<1>(GetStringMessage());
	std::cout << s1 << std::endl;
	std::cout << s2 << std::endl;

	std::cin.get();
	return 0;
}

#include <iostream>
#include <utility>
#include <functional>

std::pair<std::string, std::string> GetStringMessage()
{
	std::string s1Out = "Pcop!";
	std::string s2Out = "NIUbi!";
	return std::make_pair(s1Out, s2Out);
}

int main()
{
	auto source = GetStringMessage();
	std::string s1 = source.first;
	std::string s2 = source.second;
	std::cout << s1 << std::endl;
	std::cout << s2 << std::endl;

	std::cin.get();
	return 0;
}