C# convert integer to hex and back again

Question

How can I convert the following?

2934 (integer) to B76 (hex)

Let me explain what I am trying to do. I have User IDs in my database that are stored as integers. Rather than having users reference their IDs I want to let them use the hex value. The main reason is because it's shorter.

So not only do I need to go from integer to hex but I also need to go from hex to integer.

Is there an easy way to do this in C#?

Answer 1

int myInt = 2934;
string myHex = myInt.ToString("X");  // gives you hex
int myNewInt = Convert.ToInt32(myHex, 16);  // back to int again.

see here for more info & examples - http://msdn.microsoft.com/en-us/library/bb311038.aspx.

Answer 2

string HexFromID(int ID)
{
    return ID.ToString("X");
}

int IDFromHex(string HexID)
{
    return int.Parse(HexID, System.Globalization.NumberStyles.HexNumber);
}

I really question the value of this, though. You're stated goal is to make the value shorter, which it will, but that isn't a goal in itself. You really mean either make it easier to remember or easier to type.

If you mean easier to remember, then you're taking a step backwards. We know it's still the same size, just encoded differently. But your users won't know that the letters are restricted to 'A-F', and so the ID will occupy the same conceptual space for them as if the letter 'A-Z' were allowed. So instead of being like memorizing a telephone number, it's more like memorizing a GUID (of equivalent length).

If you mean typing, instead of being able to use the keypad the user now must use the main part of the keyboard. It's likely to be more difficult to type, because it won't be a word their fingers recognize.

A much better option is to actually let them pick a real username.

Answer 3

Try the following to convert it to hex

public static string ToHex(this int value) {
  return String.Format("0x{0:X}", value);
}

And back again

public static int FromHex(string value) {
  if ( value.StartsWith("0x", StringComparison.OrdinalIgnoreCase)) {
    value = value.SubString(2);
  }
  return Int32.Parse(value, NumberStyles.HexNumber);
}

Answer 4

// Store integer 182
int decValue = 182;
// Convert integer 182 as a hex in a string variable
string hexValue = decValue.ToString("X");
// Convert the hex string back to the number
int decAgain = int.Parse(hexValue, System.Globalization.NumberStyles.HexNumber);

from http://www.geekpedia.com/KB8_How-do-I-convert-from-decimal-to-hex-and-hex-to-decimal.html

Answer 5

To Hex:

string hex = intValue.ToString("X");

To int:

int intValue = int.Parse(hex, System.Globalization.NumberStyles.HexNumber)

Answer 6

A fashionably belated response, but have you considered some sort of Integer shortening implementation? If the only goal is to make the user ID as short as possible, I'd be interested to know if there is any other apparent reason why you specifically require hexadecimal conversion - unless I missed it of course. Is it clear and known (if so required) that user IDs are in actual fact a hexadecimal representation of the real value?