c#时间计算

        DateTime start = new DateTime(2010, 8, 25, 8, 0, 0);
        DateTime end = new DateTime(2010, 8, 25, 16, 0, 0);
        Console.WriteLine((end - start).TotalHours);

对于字符串:

        DateTime start = DateTime.Parse("8:00");
        DateTime end = DateTime.Parse("16:00");
        Console.WriteLine((end - start).TotalHours);

我想出了这个夏令时安全的方法。该函数适用于UTC和本地时区。如果 DateTimeKind Unspecified 在任何一个输入上,返回值都是未定义的(这是一种奇怪的说法,可能不正确)。

private double TotalHours(DateTime earliest, DateTime latest)
{
    earliest = (earliest.Kind == DateTimeKind.Local) ? earliest.ToUniversalTime() : earliest;
    latest = (latest.Kind == DateTimeKind.Local) ? latest.ToUniversalTime() : latest;
    return (latest - earliest).TotalHours;
}

System.DateTime punchIn = new System.DateTime(2010, 8, 25, 8, 0, 0);

System.DateTime punchOut = new System.DateTime(2010, 8, 25, 16, 0, 0);

System.TimeSpan diffResult = punchOut.Subtract(punchIn);

TimeSpan.TotalHours :

TimeSpan difference = datetime2 - datetime1;
double totalHours = difference.TotalHours;

TotalHours 结果的属性 Timespan

    DateTime start = new DateTime(2010, 8, 25, 8, 0, 0);
    DateTime end = new DateTime(2010, 8, 25, 16, 0, 0);
    int hours = end.Subtract(start).TotalHours;