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我對C++比較陌生，但對編程不太熟悉，我很困惑，爲什麼我在C++程序中遇到這個非常奇怪的問題。While while循環的問題C++
while (runUserInputLoop)
{
displayMenu();
cout << "Enter the number that corresponds with your choice from the menu: ";
getline(cin, menuLoopChoice);
if (menuLoopChoice == "1")
{
cout << "Enter mean: ";
cin >> mean;
cout << "Enter z-score: ";
cin >> z;
cout << "Enter standard deviation: ";
cin >> stDev;
cout << "Enter sample size: ";
cin >> n;
oneSampZInt(mean, z, stDev, n);
}
else if (menuLoopChoice == "2")
{
cout << "Enter mean: ";
cin >> mean;
cout << "Enter t-score: ";
cin >> t;
cout << "Enter standard deviation: ";
cin >> stDev;
cout << "Enter sample size: ";
cin >> n;
oneSampTInt(mean, t, stDev, n);
}
else if (menuLoopChoice == "3")
{
cout << "Enter mean for first sample: ";
cin >> mean1;
cout << "Enter mean for second sample: ";
cin >> mean2;
cout << "Enter standard deviation for first sample: ";
cin >> stDev1;
cout << "Enter standard deviation for second sample: ";
cin >> stDev2;
cout << "Enter z-score: ";
cin >> z;
cout << "Enter size of first sample: ";
cin >> n1;
cout << "Enter size of second sample: ";
cin >> n2;
indepMeansZInt(mean1, mean2, stDev2, stDev1, n1, n2, z);
}
else if (menuLoopChoice == "4")
{
cout << "Enter mean for first sample: ";
cin >> mean1;
cout << "Enter mean for second sample: ";
cin >> mean2;
cout << "Enter standard deviation for first sample: ";
cin >> stDev1;
cout << "Enter standard deviation for second sample: ";
cin >> stDev2;
cout << "Enter t-score: ";
cin >> t;
cout << "Enter size of first sample: ";
cin >> n1;
cout << "Enter size of second sample: ";
cin >> n2;
indepMeansTInt(mean1, mean2, stDev2, stDev1, n1, n2, t);
}
else if (menuLoopChoice == "5")
{
cout << "Enter sample proportion: ";
cin >> p;
cout << "Enter sample size: ";
cin >> n;
cout << "Enter z-score";
cin >> z;
onePropZInt(p, n, z);
}
else if (menuLoopChoice == "6")
{
cout << "Enter proportion from sample one: ";
cin >> p1;
cout << "Enter proportion from sample two: ";
cin >> p2;
cout << "Enter size of sample one: ";
cin >> n1;
cout << "Enter size of sample two: ";
cin >> n2;
cout << "Enter z-score";
cin >> z;
twoPropZInt(p1, p2, n1, n2, z);
}
else if (menuLoopChoice == "7")
{
cout << "Enter chi-sqaured right value: ";
cin >> chiSqrdRight;
cout << "Enter chi-sqaured left value: ";
cin >> chiSqrdLeft;
cout << "Enter sample variance: ";
cin >> variance;
cout << "Enter sample size: ";
cin >> n;
chiSqrdInt(chiSqrdRight, chiSqrdLeft, variance, n);
}
else if (menuLoopChoice == "8")
{
cout << "Enter mean of differences: ";
cin >> DBar;
cout << "Enter standard deviation of differences: ";
cin >> SD;
cout << "Enter number of matched pairs: ";
cin >> n;
cout << "Enter t-score: ";
cin >> t;
matchedPairsTInt(DBar, SD, n, t);
}
else if (menuLoopChoice == "A" || menuLoopChoice == "a")
{
cout << "Enter population mean: ";
cin >> mean1;
cout << "Enter sample mean: ";
cin >> mean2;
cout << "Enter population standard deviation: ";
cin >> stDev;
cout << "Enter size of sample: ";
cin >> n;
cout << "Enter z-score: ";
cin >> z;
oneSampZTest(mean1, mean2, stDev, n, z);
}
else if (menuLoopChoice == "B" || menuLoopChoice == "b")
{
cout << "Enter mean of sample one: ";
cin >> mean1;
cout << "Enter mean of sample two: ";
cin >> mean2;
cout << "Enter standard deviation of population one: ";
cin >> stDev1;
cout << "Enter standard deviation of population two: ";
cin >> stDev2;
cout << "Enter size of sample one: ";
cin >> n1;
cout << "Enter size of sample two: ";
cin >> n2;
cout << "Enter z-score: ";
cin >> z;
twoSampZTest(mean1, mean2, stDev1, stDev2, n1, n2, z);
}
else if (menuLoopChoice == "C" || menuLoopChoice == "c")
{
cout << "Enter population mean: ";
cin >> mean1;
cout << "Enter sample mean: ";
cin >> mean2;
cout << "Enter sample standard deviation: ";
cin >> stDev;
cout << "Enter size of sample: ";
cin >> n;
cout << "Enter t-score: ";
cin >> t;
oneSamptTest(mean1, mean2, stDev, n, z);
}
else if (menuLoopChoice == "D" || menuLoopChoice == "d")
{
cout << "Enter mean of sample one: ";
cin >> mean1;
cout << "Enter mean of sample two: ";
cin >> mean2;
cout << "Enter standard deviation of sample one: ";
cin >> stDev1;
cout << "Enter standard deviation of sample two: ";
cin >> stDev2;
cout << "Enter size of sample one: ";
cin >> n1;
cout << "Enter size of sample two: ";
cin >> n2;
cout << "Enter t-score: ";
cin >> t;
twoSamptTest(mean1, mean2, stDev1, stDev2, n1, n2, t);
}
else if (menuLoopChoice == "E" || menuLoopChoice == "e")
{
cout << "Enter the population proportion: ";
cin >> p1;
cout << "Enter the sample proportion: ";
cin >> p2;
cout << "Enter the sample size: ";
cin >> n;
cout << "Enter the z-score: ";
cin >> z;
onePropZTest(p1, p2, n, z);
}
else if (menuLoopChoice == "F" || menuLoopChoice == "f")
{
cout << "Enter sample proportion one: ";
cin >> p1;
cout << "Enter sample proportion two: ";
cin >> p2;
cout << "Enter the x value of proportion one: ";
cin >> x1;
cout << "Enter the x value of proportion two: ";
cin >> x2;
cout << "Enter the size of sample one: ";
cin >> n1;
cout << "Enter the size of sample two: ";
cin >> n2;
cout << "Enter the z-score: ";
cin >> z;
twoPropZTest(p1, p2, x1, x2, n1, n2, z);
}
else if (menuLoopChoice == "q" || menuLoopChoice == "Q")
{
runUserInputLoop = false;
}
}
通過循環的第一次迭代，一切工作正常。但是，在所有後續的迭代中，循環似乎只重複一次，沒有任何輸入，然後再次，讓我再次輸入輸入。所以基本上，有可能導致它執行兩次while循環的這部分額外的迭代：
displayMenu();
cout << "Enter the number that corresponds with your choice from the menu: ";
getline(cin, menuLoopChoice);
這裏是它的外觀在控制檯中的圖片：
。粗略地圈出來的部分是「幽靈迭代」。我覺得它應該是簡單的，但我對C++還不是非常熟悉，所以我很難過。如有必要，該程序的完整代碼可用here。
您將「cin」問題描述爲「while循環」問題意味着您對一些奇怪的錯誤假設感到困惑。我沒有仔細研究你的帖子，看到**爲什麼**在前一次迭代的輸入緩衝區中留下了一些內容，以混淆下一次迭代。但你不需要知道爲什麼要看到這種情況。 – JSF
當你喜歡時，你可以清除'cin'，如果程序是交互式的，你可以在提示下一個輸入之前通過清除'cin'使它更加健壯。如果輸入可能提前輸入或重定向輸入，則需要在輸入下一行之前確保每行輸入已完全消耗。 – JSF
或者，這可能更有可能，我前面提到的對C++編程的熟悉程度不夠，導致我對while循環問題的cin問題感到困惑，而實際上這不是假設的結果，無論是奇怪的還是不正確的。 – wjjd225