雙重乘法正在四舍五入，我不知道如何解決

Question

我的代碼將我的double值四舍五入，將兩個double相乘，然后將其四舍五入為整數值。 有人可以幫忙嗎？

cout << "This program will determine the water needs for "
        "a refugee camp based on the number of refugees, "
        "daily water needs, and the existing water supplies."
        << endl
        << "Please enter the number of refugees: " << endl;

double NumOfRefugees = 0;
cin >> NumOfRefugees;

cout << "Please enter the daily water needs for each person "
        "(in the range 7.5 to 15.0 liters per day.): " << endl;

double DailyNeedsPerPerson = 0;
cin >> DailyNeedsPerPerson;

if (DailyNeedsPerPerson < 7.5 || DailyNeedsPerPerson > 15.0)
{
    cout << "The entered value is not within a reasonable range as specified in "
            "the Sphere Project Humanitarian Charter. The program will now end.";
    return 1;
}

double TotalDailyDemand = NumOfRefugees * DailyNeedsPerPerson;

cout << "The total demand is " << TotalDailyDemand << endl;

例如，當我輸入15934和9.25時，我的代碼輸出：

This program will determine the water needs for a refugee camp based on the number of refugees, daily water needs, and the existing water supplies.
Please enter the number of refugees: 
15934
Please enter the daily water needs for each person (in the range 7.5 to 15.0 liters per day.): 
9.25
147390
The total demand is 147390

請幫忙！

Answer 1

您所看到的是輸出流的默認精度為6位數字的結果。

因此，您需要對輸出流應用某種格式，以便查看多於默認的6位數字。 例如：

#include <iostream>

int main()
{
    double x = 15934.0;
    double y = 9.25;
    double z = x*y;

    std::cout.setf(std::ios_base::fixed, std::ios_base::floatfield);
    std::cout.precision(2);
    std::cout << z;
}

產量

147389.50

對setf的調用用於指定固定的浮點格式，並在小數點后使用指定的位數。 對precision的調用指定小數點后的位數。

我不確定您實際上想要什么格式，因為您沒有說。 但是這些功能以及親戚應該可以讓您獲得所需的結果。