Ignore milliseconds when comparing two datetimes

Question

This is probably a dumb question, but I cannot seem to figure it out. I am comparing the LastWriteTime of two files, however it is always failing because the file I downloaded off the net always has milliseconds set at 0, and my original file has an actual value. Is there a simple way to ignore the milliseconds when comparing?

Here's my function:

//compare file's dates public bool CompareByModifiedDate(string strOrigFile, string strDownloadedFile) {      DateTime dtOrig = File.GetLastWriteTime(strOrigFile);      DateTime dtNew = File.GetLastWriteTime(strDownloadedFile);       if (dtOrig == dtNew)         return true;      else         return false; } 

Thanks in advance

Answer 1

I recommend you use an extension method:

public static DateTime TrimMilliseconds(this DateTime dt) {     return new DateTime(dt.Year, dt.Month, dt.Day, dt.Hour, dt.Minute, dt.Second, 0, dt.Kind); } 

then its just:

if (dtOrig.TrimMilliseconds() == dtNew.TrimMilliseconds()) 

Answer 2

Care should be taken, if dt has non-zero microseconds (fractions of millis). Setting only milliseconds to zero is not enough.
To set millis and below to zero (and get a succesfull comparison), the code would be:

dt = dt.AddTicks(-dt.Ticks % TimeSpan.TicksPerSecond); // TimeSpan.TicksPerSecond=10000000