CODEWITHSUNDEEP
c#inttype-conversionbyte
milnuts
milnuts

Reputation: 427

Unhandled exception converting to byte

As the title implies, I'm getting "An unhandled exception of type 'System.FormatException'" style message. Need some help figuring out why. I'm reading in a file that has a hex value I need to parse. The value I'm reading it could look something like this "0x12345678" (4 bytes in length).

The first byte (note this is little endian) is 'BE' and I can get that no problem. My issue is then trying to take the next three bytes and convert that into a human readable int. (Long story, but the program that generates the output I'm parsing takes a human readable decimal number and converts it to this LE nonsense.)

    string parmVal = lineF.Substring((pos + length));  // this is "0x12345678"

    string hexID = parmVal.Substring(2, 2);   // stores '12'

    byte[] testID = new byte[4];
    testID[0] = Convert.ToByte(parmVal.Substring(4, 2));  <----error here
    testID[1] = Convert.ToByte(parmVal.Substring(6, 2));
    testID[2] = Convert.ToByte(parmVal.Substring(8, 2));
    testID[3] = Convert.ToByte(0);

    decimalID = int.Parse(hexID, System.Globalization.NumberStyles.HexNumber);  // stores 18 (0x12)
    testIDNumber = BitConverter.ToInt32(testID,0);  // stores 345678

Interestingly, in the code I later output these values to a CSV file, and the values I print out look correct, even though its throwing the exception. I tried reading in the last 3 bytes the same way as the first by, but then when I do the int.Parse() on it, it gets its endian-ness backwards. Where I'd want it to convert 0x"785634", its converting 0x"345678".

Upvotes: 1

Views: 605

Answers (1)

Dmytro Bardai
Dmytro Bardai

Reputation: 154

Try to specify base in Convert.ToByte call.

In your case it has to be:

testID[0] = Convert.ToByte(parmVal.Substring(4, 2), 16);

Upvotes: 1

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