How to convert byte[] to datetime

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Hi i am reading the current DateTime to byte array how to convert the byte array back to DateTime ?

What I have tried:

C#

public static byte ConvertToBcd(byte x)
{

    int msb = x / 10;

    int lsb = x - (msb * 10);

    msb = msb << 4;

    return (byte)(msb | lsb);

}


public static byte[] GetLocalTimeInBCD()
{

    DateTime now = DateTime.Now;

    byte[] Data = new byte[4];

    Data[0] = (byte)(now.Year - 100);

    Data[1] = (byte)now.Month;

    Data[2] = (byte)now.Day;

    Data[3] = (byte)now.Hour;


    for (int i = 0; i < 4; i++)
    {

        Data[i] = ConvertToBcd(Data[i]);

    }

    return Data;

}

Posted 17-Nov-16 22:44pm

Alex Sprint

Updated 17-Nov-16 23:17pm

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Comments

Philippe Mori 18-Nov-16 10:22am

now.Year - 100 is suspicious. Year in date time are "four digits". So we are in 2016 and not in 16 or 116...

Alex Sprint 20-Nov-16 23:25pm

I agree but to check whether the byte[] conversion is correct i have to convert it back to DateTime. Hence i am seeking for an assistance.

Philippe Mori 20-Nov-16 23:46pm

2016 - 100 would give 1916 which would overflow a byte. It serve no useful purpose to fix the conversion to BCD if the input is wrong. The problem would be even worst in BCD as BCD could only represent 100 numbers... In that case, it won't give a valid BCD number.

Alex Sprint 20-Nov-16 23:59pm

Hi Philippe can you help me out on how to get the current DateTime and convert to 4 Byte[] ?

2 solutions

Solution 2

Well you have just to revert the process. Start with

C#

public static byte ConvertFromBcd(byte bcd)
 {
   return (byte) ((bcd >> 4) * 10 + (bcd & 0XF));
 }

Posted 17-Nov-16 23:17pm

CPallini

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Er. Puneet Goel · Accepted Answer · 2016-11-17T22:51:00

Solution 1

The FromBinary method takes a long value that is created using the ToBinary method. It contains the Kind and Ticks components, and this is not what a database timestamp contains.

Using BitConverter to get the long value is correct, but then you have to take the time origin for the time stamp and add the long value as the correct unit. Assuming it's a timestamp from a MySQL database, IIRC it's the number of milliseconds from 1980-01-01:

C#

//Convert DateTime to bytes (always convert datetime to ticks)
byte[] byteValue = BitConverter.GetBytes(DateTime.Now.Ticks);
//Convert datetime to longvalue
long longVar = BitConverter.ToInt64(byteValue, 0);
//Convert to datetime.
DateTime dateTimeVar = new DateTime(longVar);

Posted 17-Nov-16 22:51pm

Er. Puneet Goel

Updated 20-Nov-16 22:11pm

v2

Comments

Alex Sprint 20-Nov-16 23:28pm

Hey puneet I am converting whole DateTime.Now to byte[] i need to convert it back to DateTime.

Er. Puneet Goel 21-Nov-16 0:34am

//Convert DateTime to bytes (always convert datetime to ticks)
byte[] byteValue = BitConverter.GetBytes(DateTime.Now.Ticks);
//Convert datetime to longvalue
long longVar = BitConverter.ToInt64(byteValue, 0);
//Convert to datetime.
DateTime dateTimeVar = new DateTime(longVar);

Alex Sprint 21-Nov-16 1:46am

Hi puneet Thanks for your suggestion.
How to mark this as solution ?

Er. Puneet Goel 21-Nov-16 4:11am

Dear, Just accept the the Solution 1 above as solution. I have just updated solution.