如何循环变量？

Question

我已经制作了一个“程序”，只是说欢迎！键入要彼此相加的两个数字： 在那里你输入两个数字然后你得到答案...... 完成后，它会说： Press any key to continue 。 . . 当您按下某个键时，程序会关闭，但我希望它在您按下任何键时重新启动... 我怎么做？我将 Microsoft Visual Studio Express 2013 用于 Windows 桌面... 语言是 C++

这是我的代码：

 #include <iostream>
   #include <limits>
   #include <cstdio>
   using namespace std;

   int Add(int x, int y)
   {


        cout << "Calculating the sum of " << x << " + " << y << "\n";
        return (x + y);
    }

     int main()
     {
         cout << " Welcome!\n";
         int a, b, c;
         cout << "Type two numbers you want to be added to each other: ";
         cin >> a;
         cin >> b;
         c = Add(a, b);
         cout << "The answere is: " << c;
         cout << "\nShutting down....\n\n";
         system("pause");
         return 0;
    }

Answer 1

要循环，你可以使用while。

例如：

while (false) {
    std::cout << "You will never see this output" << std::endl;
}

bool loop = true;
while (loop) {
    std::cout << "Type 'quit' to quit this loop." << std::endl;
    std::string input;

    // This will grab a *single word* from the input. If you want a line, look
    // at std::getline
    std::cin >> input;
    if (input == "quit") {
        loop = false;
    }
}

while (true) {
    std::cout << "This will be repeated forever" << std::endl;
}

还有另外两种形式，do while：

std::string input;
do {
    std::cout << "Type 'quit' to quit." << std::endl;
    std::cin >> input;
} while (input != "quit");

...和for（通常用于循环定义的事物列表）：

for (size_t i = 0; i < 10; ++i) {
    std::cout << i << " out of 10" << std::endl;
}

从技术上讲，您可以将这些循环类型中的任何一种用于任何类型的循环，但我怀疑您想要的类型是两个标准无限循环之一（无论您喜欢哪个）：

while (true) {
    // stuff to repeat forever
}

for (;;) {
    // stuff to repeat forever
}

... 或类似于上述do { ... } while (input != "quit"); 循环的do while 循环。

Answer 2

     int main()
     {
         cout << " Welcome!\n";
         int a, b, c;
         while (true)
         {
             cout << "Type two numbers you want to be added to each other: ";
             cin >> a;
             cin >> b;
             c = Add(a, b);
             cout << "The answere is: " << c;
             cout << "\nPress a key to go again....\n\n";
             system("pause");
         };
         return 0;
    }

Answer 3

你可以这样做：

     int main()
     {
         cout << " Welcome!\n";
         int a, b, c;

         while(true) {
             cout << "Type two numbers you want to be added to each other: ";
             cin >> a;
             cin >> b;
             c = Add(a, b);
             cout << "The answere is: " << c;
             cout << "\nPress any key to continue\n";
             system("pause");
         }
         return 0;
    }

Answer 4

使用 do while 循环提及您的情况 在退出程序之前，以便您可以确定何时继续以及何时退出

Answer 5

我不确定我是否理解您的问题，但我认为这就是您要寻找的。有一个布尔值来确定程序是否会循环。

int main() {
    // stillRun is true while we want to keep looping the program 
    boolean stillRun = true; 

    while(stillRun) { 
        runProgram() ; // this function has all the other code in your old main() function
        cin >> stillRun ; 
    }   
}