33.promise future多线程通信

 1 #define _CRT_SECURE_NO_WARNINGS
 2 #include <iostream>
 3 #include <thread> 
 4 #include <future>
 5 #include <string>
 6 #include <cstdlib>
 7 using namespace std;
 8 
 9 promise <string>val;//全局通信变量
10 void main()
11 {
12     //字符串相加
13     /*string str1("123");
14     string str2("34");
15     string str3(str1 + str2);
16     cout << str3 << endl;*/
17 
18     thread th1([]() 
19     {
20         future<string> str = val.get_future();//获取未来状态
21         cout << "等待中" << endl;
22         //阻塞等待
23         cout << str.get() << endl;
24     }
25     );
26 
27     thread th2([]() 
28     {
29         system("pause");
30         val.set_value("hello");
31     }
32     );
33 
34     th1.join();
35     th2.join();
36     cin.get();
37 }