即使使用break时，C++开关也会切换为默认值；

Question

这是我高中编程课的作业，我似乎没有做错什么。然而，当我在VS express 2013中运行Windows调试器时，所有的情况都是默认的，即使我在所有的情况下都有break;。我不知道我做错了什么，也根本查不出来。

// mauroc_switch.cpp : Defines the entry point for the console application.
//

#include "stdafx.h"
#include<iostream>

using namespace std;

int main()
{
char yesform;
cout << "Type ''yes,'' lowercased and romanized, in a non-English language." << endl;
cin >> yesform;

//***Here is the switch statement.***

switch (yesform){
case 'yes':
    cout << "This is the English ''yes.'' Please type a non-English version of ''yes.'' " << endl;
    break;
case 'ja':
    cout << "This is the German form of ''yes.'' It is also the Swedish and Norwegian form of ''yes.'' " << endl;
    break;
case 'si':
    cout << "This is both the Spanish and the Italian form of ''yes.'' " << endl;
    break;
case 'oui':
    cout << "This is the French form of ''yes.'' " << endl;
    break;
case 'hai':
    cout << "This is the Japanese form of ''yes.'' " << endl;
    break;
case 'da':
    cout << "This is the Russian form of ''yes.'' " << endl;
    break;
case 'ne':
case 'ye':
    cout << "This is a Korean form of ''yes.'' " << endl;
    break;
case 'naam':
case 'aiwa':
    cout << "This is an Arabic form of ''yes.'' " << endl;
    break;
case 'sim':
    cout << "This is the Portuguese form of ''yes.'' " << endl;
    break;
case 'haan':
    cout << "This is the Hindi form of ''yes.'' " << endl;
    break;
default:
    cout << "You either made a typo or you typed ''yes'' in an unsupported language. Please try again. ";
    break;
}

system("pause");
return 0;
}

Answer 1

您正在混合字符和字符串。遗憾的是，C++允许使用像'yes'这样的“字符”，但这并不是您所想的那样。另一个问题是，一旦切换到字符串(std::string)，就不能再使用switch，但是需要一系列if-else语句或其他方法来匹配字符串。

这里有一个简单的例子，应该是可行的：

#include <iostream>
#include <string>

using namespace std;

int main()
{
    string yesform;
    cout << "Type ''yes,'' lowercased and romanized, in a non-English language." << endl;
    cin >> yesform;

    if( yesform == "yes" )
        cout << "This is the English ''yes.'' Please type a non-English version of ''yes.'' " << endl;
    else if( yesform == "ja" )
        cout << "This is the German form of ''yes.'' It is also the Swedish and Norwegian form of ''yes.'' " << endl;
    else
        cout << "You either made a typo or you typed ''yes'' in an unsupported language. Please try again. ";

    return 0;
}

在您的示例中，一旦将输入读入字符串，请尝试使用std::map将输入映射到输出字符串。对于上面的示例来说，这可能就足够了，它将使代码更具可读性。

Answer 2

如果你必须在这个赋值中使用switch case，那么在你的switch语句之前，你必须将字符串‘转换’成一个整数值。一个这样的例子是...

enum yesLanguage {YES, JA, OUI, ..., CI};

yesLanguage yesAnswer = YES;

if (yesform == 'yes'){
     yesAnswer = YES;
}

else if(yesform == 'ja'){
     yesAnswer = JA;
}

以此类推，然后在您的交换机情况下，您将拥有

switch(yesLanguage)
   case YES:
      Your YES output here;
      break;
   case JA: 
      .........

以此类推，剩下的代码就像你的原始帖子中的上面那样。

但是，如果您不需要来使用切换大小写，那么就像我上面的帖子中所说的那样，使用if /方法。

编辑以添加枚举。 http://en.cppreference.com/w/cpp/language/enum