find time from four bytes

Question

program in c# find time : byte [] a = new byte { 224 , 198 , 23 , 200 }; Console . WriteLine ( "time {0} " , BitConverter . ToInt32 ( a , 0 )); output: -939765856 what wrong in program ,i use Convert.ToDateTime but not has correct output i want a 32 bit integer that specifies(in seconds since midnight,january 1, 1904)

Vulpes · Answer

Well, as the result can't be negative, may be the bytes represent an unsigned integer rather than a signed integer? If we assume that we get: byte[] a = new byte[] {224,198,23,200}; uint ui = BitConverter.ToUInt32(a,0); DateTime dt = new DateTime(1904, 1, 1); dt = dt.AddSeconds(ui); Console.WriteLine(dt); This gives 03:24:00 on 18 May 2010.

Vulpes · Answer

Yes, you can use any 'base' date you like. I only used 1/1/1904 because this was the date you used yourself in your opening post.

zozo ahmed · Answer

thank you so much ,but why use 1904 can i use (1980,1,1)?? i am beginner in c# and i need to understand why use year (1904)

Vulpes · Answer

We need to work backwards to find the equivalent byte array for that. Ignoring any adjustment for local time/UTC: DateTime dt = new DateTime(1904, 1, 1); DateTime dt2 = new DateTime(2013, 9, 9, 11, 52, 0); uint ui = (uint)(dt2 - dt).TotalSeconds; byte[] a = BitConverter.GetBytes(ui); foreach(byte b in a) Console.Write("{0} ", b); This gives: 224 102 83 206

zozo ahmed · Answer

ok thanks,can time gives 9/9/2013 11:52:00

find time from four bytes

Answers (5)