非对称算术舍入

引言

.NET 舍入仅限于银行家舍入法。我到处搜索替代方案，但没有找到。可能还有更好的方法，但我认为这种方法非常轻量级和简单。

要点：1 - 4：向下舍入，5 - 9：向上舍入。只需将这些函数添加到类、窗体或任何你正在编写的程序中，并在需要进行舍入时调用它们即可。

public static float aaRounding(float numToRound, int numOfDec)
{
    return (float)aaRounding((decimal)numToRound, numOfDec);
}

public static double aaRounding(double numToRound, int numOfDec)
{
    return (double)aaRounding((decimal)numToRound, numOfDec);
}
  
public static decimal aaRounding(decimal numToRound, int numOfDec)
{
    if (numOfDec < 0)
    {
        throw new ArgumentException("BetterMath.Rounding:" + 
              " Number of decimal places must be 0 or greater", 
              "numOfDec");
    }

    decimal num = numToRound;

    //Shift the decimal to the right the number 
    //of digits they want to round to
    for (int i = 1; i <= numOfDec; i++)
    {
        num *= 10;
    }

    //Add/Subtract .5 to TRY to increase the number 
    //that is to the LEFT of the decimal
    if (num < 0)
    {
        num -= .5M;
    }
    else
    {
        num += .5M;
    }

    //Cut off the decimal, you have your answer!
    num = (decimal)((int)num);

    //Shift the decimal back into its proper position
    for (int i = 1; i <= numOfDec; i++)
    {
        num /= 10;
    }

    return num;

}