在 C++ 中获取百分比时遇到问题

Question

这里是 C++ 初学者。我正在尝试复制此输出，我快要完成了，但我在最后一部分（测验百分比）上遇到了问题。

 Example    output:
 Welcome to our math quiz program! Please enter the answers to the
 following questions:
 5! = 5
 (2^(2^(2^2))) = 65536
 3 * (4 + 8) / ((4 * 2) / (5 – 1)) = 18
 3 + 2 + 1 + 2 + 3 = 11
 Number of correct answers: 3
 Number of incorrect answers: 1
 Quiz percentage: 75%

到目前为止，这是我的代码：

int problem4() {
int numCorrect = 0;
int numIncorrect = 0;
int possibleCorrect = 4;

int correctAnswerOne = 120;
int correctAnswerTwo = 65536;
int correctAnswerThree = 18;
int correctAnswerFour = 11;

int guessOne;
int guessTwo;
int guessThree;
int guessFour;

cout << "*** Start of problem 4 ***" << endl;
cout << "Welcome to our math quiz program!" << endl;
cout << "Please enter the answers to the following questions: " << endl;
cout << "5! = ";
cin >> guessOne;
cout << "(2^(2^(2^2))) = ";
cin >> guessTwo;
cout << "3 * (4 + 8) / ((4 * 2) / (5 - 1)) = ";
cin >> guessThree;
cout << "3 + 2 + 1 + 2 + 3 = ";
cin >> guessFour;

switch (guessOne) {
    case 120:
        numCorrect++;
        break;
    default:
        numIncorrect++;
}

switch (guessTwo) {
case 65536:
    numCorrect++;
    break;
default:
    numIncorrect++;
}

switch (guessThree) {
case 18:
    numCorrect++;
    break;
default:
    numIncorrect++;
}

switch (guessFour) {
case 11:
    numCorrect++;
    break;
default:
    numIncorrect++;
}

cout << "Number of correct answers: " << numCorrect << endl;
cout << "Number of incorrect answers: " << numIncorrect << endl;
cout << "Quiz percentage: " << (numCorrect / possibleCorrect) * 100 << "%" << endl;
cout << endl;

return 0;
}

似乎当我正确回答所有问题时，我得到了 100% 的分数，但是，当我得分以外的任何分数（只有 1、2 或 3 正确）时，我最终得到 0%，因为结果。我以为我正确地进行了百分比计算，但输出却另有建议。有人能指出我正确的方向吗？谢谢

编辑：为开关添加了中断（但是，不是问题的根源）。

Answer 1

切换时需要中断，先乘以 100.0 以隐式地将第一个表达式提升为双精度数，然后除法：

int problem4() {
int numCorrect = 0;
int numIncorrect = 0;
int possibleCorrect = 4;

int correctAnswerOne = 120;
int correctAnswerTwo = 65536;
int correctAnswerThree = 18;
int correctAnswerFour = 11;

int guessOne;
int guessTwo;
int guessThree;
int guessFour;

cout << "*** Start of problem 4 ***" << endl;
cout << "Welcome to our math quiz program!" << endl;
cout << "Please enter the answers to the following questions: " << endl;
cout << "5! = ";
cin >> guessOne;
cout << "(2^(2^(2^2))) = ";
cin >> guessTwo;
cout << "3 * (4 + 8) / ((4 * 2) / (5 - 1)) = ";
cin >> guessThree;
cout << "3 + 2 + 1 + 2 + 3 = ";
cin >> guessFour;

switch (guessOne) {
case 120:
    numCorrect++;
    break;
default:
    numIncorrect++;
}

switch (guessTwo) {
case 65536:
    numCorrect++;
    break;
default:
    numIncorrect++;
}

switch (guessThree) {
case 18:
    numCorrect++;
    break;
default:
    numIncorrect++;
}

switch (guessFour) {
case 11:
    numCorrect++;
    break;
default:
    numIncorrect++;
}

cout << "Number of correct answers: " << numCorrect << endl;
cout << "Number of incorrect answers: " << numIncorrect << endl;
cout << "Quiz percentage: " << (numCorrect * 100.0 / possibleCorrect) << "%" << endl;
cout << endl;

return 0;
}

虽然为了这个目的，一个简单的 if/else 会更容易阅读：

int problem4() {
int numCorrect = 0;
int numIncorrect = 0;
int possibleCorrect = 4;

int correctAnswerOne = 120;
int correctAnswerTwo = 65536;
int correctAnswerThree = 18;
int correctAnswerFour = 11;

int guessOne;
int guessTwo;
int guessThree;
int guessFour;

cout << "*** Start of problem 4 ***" << endl;
cout << "Welcome to our math quiz program!" << endl;
cout << "Please enter the answers to the following questions: " << endl;
cout << "5! = ";
cin >> guessOne;
cout << "(2^(2^(2^2))) = ";
cin >> guessTwo;
cout << "3 * (4 + 8) / ((4 * 2) / (5 - 1)) = ";
cin >> guessThree;
cout << "3 + 2 + 1 + 2 + 3 = ";
cin >> guessFour;
if( guessOne == 120 ) ++numCorrect; else ++numIncorrect;
if( guessTwo == 65536 ) ++numCorrect; else ++numIncorrect;
if( guessThree == 18 ) ++numCorrect; else ++numIncorrect;
if( guessFour == 11 ) ++numCorrect; else ++numIncorrect;

cout << "Number of correct answers: " << numCorrect << endl;
cout << "Number of incorrect answers: " << numIncorrect << endl;
cout << "Quiz percentage: " << (numCorrect * 100.0 / possibleCorrect) << "%" << endl;
cout << endl;

return 0;
}

Answer 2

您的开关中缺少中断语句。

此外，您需要将结果类型转换为浮点型，因为所有变量都是整数。我建议你使用：

float perc;

perc = (numCorrect/possibleCorrect)*100;

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