Question

我是一名初学者，正在通过Bjarne Stroustrup的PPP书籍工作。我正在写一个简单的程序来转换货币，而且我在处理这个角色时会得到一个奇怪的角色＆＃39; e。当我在money_value和currency_type输出之间输入空格时，该程序按预期工作。所有其他＆＃34;货币＆＃34;按预期工作。有什么想法吗？

#include "../../std_lib_facilities.h"

int main()
{
    cout << "Currency conversions\n\n";
    constexpr double pound = 1.32;
    constexpr double euro = 1.17;
    constexpr double yen = 0.0089;
    double currency_value;
    char currency_type;
    cout << "Please enter a currency value followed by currency type ((e)uro, (y)en, (p)ound:\n\n";
    cin >> currency_value >> currency_type;
    cout << "\n\n";
    if (currency_type == 'e')
    {
        cout << currency_value << " euro = " << euro*currency_value << " dollars. \n\n";
    }
    else if (currency_type == 'y')
    {
        cout << currency_value << " yen = " << yen*currency_value << " dollars. \n\n";
    }
    else if (currency_type == 'p')
    {
        cout << currency_value << " pound = " << pound*currency_value << " dollars. \n\n";
    }
    else
    {
        cout << "Sorry, I don't know a currency called " << currency_type << ". \n\n";
    }
}

Answer 1

它将e视为科学数字的计算机编程表示，即6.022e+23。其他字母并不意味着什么，所以它将它们放入char中。您应该以std :: string的形式读取此货币，复制最后一个char，修剪字符串的最后一个字符，然后将字符串std :: stod转换为您的货币值。

#include "../../std_lib_facilities.h"

int main()
{
    cout << "Currency conversions\n\n";
    constexpr double pound = 1.32;
    constexpr double euro = 1.17;
    constexpr double yen = 0.0089;
    string curtemp = "";
    double currency_value;
    char currency_type;
    cout << "Please enter a currency value followed by currency type ((e)uro, (y)en, (p)ound:\n\n";
    cin >> curtemp;
    cout << "\n\n";
    currency_type = curtemp[curtemp.length()-1];
    currency_value = std::stod(curtemp.substr(0,curtemp.length()-1));
    if (currency_type == 'e')
    {
        cout << currency_value << " euro = " << euro*currency_value << " dollars. \n\n";
    }
    else if (currency_type == 'y')
    {
        cout << currency_value << " yen = " << yen*currency_value << " dollars. \n\n";
    }
    else if (currency_type == 'p')
    {
        cout << currency_value << " pound = " << pound*currency_value << " dollars. \n\n";
    }
    else
    {
        cout << "Sorry, I don't know a currency called " << currency_type << ". \n\n";
    }
}

在处理角色时获得╠符号＆＃39; e＆＃39;

1 个答案: