Question

我是编程新手，正在学习C ++课程。这是我的任务：

Write a program that continually takes in input until the user types “done”.
When the input received is a “+”, start adding together the values of each
subsequent input into a variable. When the input is a “-”, start subtracting
the values of the subsequent input from that same variable. Do nothing with
inputs that are received before either a “+” or “-” operation. Output the
final result to the screen.

这是我到目前为止所做的：

#include <iostream>
#include <string>
#include <cmath>
#include <vector>

using namespace std;

int main()
{
    string input;
    int number;
    vector<int> numbers;

    cout << "Type some stuff: \n";


    for (;cin >> input && input != "done";)
    {
        if (input == "done")
            break;
        else if (input == "+")

        cout << input;
    }



    return 0;
}

这是输出：

Type some stuff: 
Hello world done
HelloworldProgram ended with exit code: 0

我无法弄清楚下一部分。谢谢你的帮助。

Answer 1

从赋值中可以假设输入是由空格分隔的单词/数字。我认为作为赋值的一部分给出的代码行for (;cin >> input && input != "done";)支持这种假设。然后，以下输入应该实现以下输出：

100 200 + 100 200 - 10 done  --> 290

以下是实现此目的的代码：

int main()
{
    string input;
    int result;
    int mode = 0;

    cout << "Type some stuff: \n";


    for (;cin >> input && input != "done";)
    {
        if (input == "done")
            break;
        else if (input == "+")
            mode = 1;
        else if (input == "-")
            mode = -1;
        else {
            try {
                int number = stoi(input);
                number *= mode;
                result += number;
            }
            catch( const std::exception& e ) {  }  // ignore any conversion errors
        }
    }

    cout << result;

    return 0;
}

不断获取输入，并在关键字后面添加输入值

1 个答案: