简单计算误差 [英] Simple Calculation Error

问题描述

这是我遇到问题的简短代码段:

Here is a short code snippet that I am having trouble with:

private double DetermineBatteryDepthOfDischarge(ComboBox DepthOfDischarge)
{
    int k = DepthOfDischarge.SelectedIndex;
    double DoD = DoD = 10 / (k + 1);
    //MessageBox.Show(DoD.ToString());
    return (DoD);
}

组合框有10个项目:10％，20％，...，90％，100％.
现在，如果我选择说组合框中的第三项(30％)，则DoD变量将存储3而不是3.33333333 ...
如果我在组合框中选择说第7项(占70％)，则mod将读取1，而不是1.42857 ...

小数点似乎被截断了.为什么会在双精度"或十进制"数据类型中发生这种情况?
我缺少重要的东西吗?

The combobox has 10 items: 10%, 20%, ... , 90%, 100%.
Now if I select say the third item (30%) in the combobox, the DoD variable stores 3 and not 3.33333333...
If I select say the 7th item, (70%) in the combobox, then the DoD reads 1 and not 1.42857...

The decimal seems to be truncated. Why is this happening in a ''double'' or ''decimal'' data type?
Am I missing something important?

推荐答案

使用浮点值而不是整数:

Use floating-point values instead of integers:

private double DetermineBatteryDepthOfDischarge(ComboBox DepthOfDischarge)
{
    double k = Convert.ToDouble(DepthOfDischarge.SelectedIndex);
    double DoD = 10.0 / (k + 1.0);
    //MessageBox.Show(DoD.ToString());
    return (DoD);
}

尝试使用double DoD = DoD = 10.0 / (k + 1.0);

private double DetermineBatteryDepthOfDischarge(ComboBox DepthOfDischarge)
{
    Double k = cdbl(DepthOfDischarge.SelectedIndex);
    Double DoD = 10.0 / (k + 1.0);
    //MessageBox.Show(DoD.ToString());
    return (DoD);
}

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