C# - Duration between two DateTimes in minutes

Question

I need to determine duration between two DateTimes in minutes.

However, there is a slight twist:

• exclude weekends
• only count minutes which a

Answer 1

My implementation :) The idea is to quickly compute the total weeks, and walk the remaining week day by day...

public TimeSpan Compute(DateTime start, DateTime end)
{
    // constant start / end times per day
    TimeSpan sevenAM = TimeSpan.FromHours(7);
    TimeSpan sevenPM = TimeSpan.FromHours(19);

    if( start >= end )
    {
        throw new Exception("invalid date range");
    }

    // total # of weeks
    int completeWeeks = ((int)(end - start).TotalDays) / 7;

    // starting total
    TimeSpan total = TimeSpan.FromHours(completeWeeks * 12 * 5);

    // adjust the start date to be exactly "completeWeeks" past its original start
    start = start.AddDays(completeWeeks * 7);

    // walk days from the adjusted start to end (at most 7), accumulating time as we can...
    for(
        // start at midnight
        DateTime dt = start.Date;

        // continue while there is time left
        dt < end;

        // increment 1 day at a time
        dt = dt.AddDays(1)
    )
    {
        // ignore weekend
        if( (dt.DayOfWeek == DayOfWeek.Saturday) ||
             (dt.DayOfWeek == DayOfWeek.Sunday) )
        {
            continue;
        }

        // get the start/end time for each day...
        // typically 7am / 7pm unless we are at the start / end date
        TimeSpan dtStartTime = ((dt == start.Date) && (start.TimeOfDay > sevenAM)) ?
            start.TimeOfDay : sevenAM;
        TimeSpan dtEndTime = ((dt == end.Date) && (end.TimeOfDay < sevenPM)) ?
            end.TimeOfDay : sevenPM;

        if( dtStartTime < dtEndTime )
        {
            total = total.Add(dtEndTime - dtStartTime);
        }
    }

    return total;
}

Answer 2

Use TimeSpan.TotalMinutes, subtract non-business days, subtract superfluous hours.

Answer 3

Try the following DiffRange function.

public static DateTime DayStart(DateTime date)
{
    return date.Date.AddHours(7);
}

public static DateTime DayEnd(DateTime date)
{
    return date.Date.AddHours(19);
}

public static TimeSpan DiffSingleDay(DateTime start, DateTime end)
{
    if ( start.Date != end.Date ) {
        throw new ArgumentException();
    }

    if (start.DayOfWeek == DayOfWeek.Saturday || start.DayOfWeek == DayOfWeek.Sunday )
    {
        return TimeSpan.Zero;
    }

    start = start >= DayStart(start) ? start : DayStart(start);
    end = end <= DayEnd(end) ? end : DayEnd(end);
    return end - start;
}

public static TimeSpan DiffRange(DateTime start, DateTime end)
{
    if (start.Date == end.Date)
    {
        return DiffSingleDay(start, end);
    }

    var firstDay = DiffSingleDay(start, DayEnd(start));
    var lastDay = DiffSingleDay(DayStart(end), end);

    var middle = TimeSpan.Zero;
    var current = start.AddDays(1);
    while (current.Date != end.Date)
    {
        middle = middle + DiffSingleDay(current.Date, DayEnd(current.Date));
        current = current.AddDays(1);
    }

    return firstDay + lastDay + middle;
}