Question

Currently, I’m returning feedback to the user in this form:

"<UserName> removed 07:00, 07:15, 07:30, 07:45, 08:00, 08:15, 08:30, 09:00, 09:15, 09:30, 09:45, 10:00, 10:15, 10:30, 11:15, (etc.)"

…Understandably, they want it to be more user-friendly, such as this instead:

<UserName> removed 07:00 - 8:30, 9:00 - 10:30, 11:15 - (etc.)

Rather than rework the whole method that concatenates these values into a StringBuilder, I’d like to take that first output and morph it into the second; something like:

sbQuarterHoursRemoved = CombineSucceedingQuarterHours(sbQuarterHoursRemoved);

Is this as tedious as it appears to me, or does somebody know a relatively painless way of accomplishing it?

UPDATE

I adapted the code below to this:

String QuarterHoursRemovedPrettified = PrettifyQuarterHoursRemoved(sbQuarterHoursRemoved);
. . .

private static string PrettifyQuarterHoursRemoved(StringBuilder sbQuarterHoursRemoved)
{
    string[] times = sbQuarterHoursRemoved.ToString().Split(',');
    DateTime prevDt = new DateTime(1);
    string prevString = "";

    StringBuilder output = new StringBuilder();
    foreach (string time in times) {
        DateTime dt = DateTime.ParseExact(time, "HH:mm", CultureInfo.InvariantCulture);
        if (dt.Subtract(prevDt).TotalMinutes > 15) {
            if (prevString != "")
                output.Append(" " + prevString + ",");
            output.Append(" " + time + " -");
        }
        prevString = time;
        prevDt = dt;
    }
    output.Remove(output.Length - 1, 1);
    return output.ToString(); 
}

With values in times like this (after the call to Split()):

00:45
01:00
01:15
22:45
23:00

It ALWAYS crashes the second pass through the loop. The first goes fine, but the second time, no matter what value, crashes.
e.g., the first time through, dt becomes:

dt = 6/26/2012 12:45 am

…after the call to ParseExact()

…but the second call to ParseExact() – with, for example, “01:00” as the value in “time” fails.

Some error details are:

*System.FormatException was unhandled
Message=String was not recognized as a valid DateTime.
Source=mscorlib
StackTrace:
at System.DateTimeParse.ParseExact(String s, String format, DateTimeFormatInfo dtfi, DateTimeStyles style)
at System.DateTime.ParseExact(String s, String format, IFormatProvider provider)
at TitanNextGen_Platypi.PlatypiMainForm.PrettifyQuarterHoursRemoved(StringBuilder sbQuarterHoursRemoved) in…*

UPDATED AGAIN

It works now – untrimmed vals were the problem. When the value was, for example, ” 01:15″ instead of “01:15” all Dallas broke loose (and I changed “hh:mm” to “HH:mm” in the call to ParseExact() to account for 24-hour time)

Answer 1

As you are processing the strings, you will need to keep track of where you are at and if you need to start a new sequence:

    string[] times = { "07:00", "07:15", "07:30", "07:45", "08:00", "08:15", "08:30", "09:00", "09:15", "09:30", "09:45", "10:00", "10:15", "10:30", "11:15" };

    private void Form1_Load(object sender, EventArgs e)
    {
        DateTime prevDt = new DateTime(1);
        string prevString = "";

        StringBuilder output = new StringBuilder("UserXyz Deleted ");
        foreach (string time in times)
        {

            DateTime dt = DateTime.ParseExact(time,"hh:mm", CultureInfo.InvariantCulture);
            if (dt.Subtract(prevDt).TotalMinutes > 15)
            {
                if (prevString != "")
                    output.Append(" " + prevString + ",");
                output.Append(" " + time + " -");
            }
            prevString = time;
            prevDt = dt;
        }
        output.Remove(output.Length - 1, 1);
        MessageBox.Show(output.ToString());
    }