how can convert string into Hexadecimal in C#.net [duplicate]

If you want to get the HEX of each number, for example Hex of 1, Hex of 2 , etc. you can do as below:

string input = "12968";
char[] values = input.ToCharArray();
foreach (char letter in values)
{
    // Get the integral value of the character. 
    int value = Convert.ToInt32(letter);
    // Convert the decimal value to a hexadecimal value in string form. 
    string hexOutput = String.Format("{0:X}", value);
    Console.WriteLine("Hexadecimal value of {0} is {1}", letter, hexOutput);
}

or if you want get the complete string as a float number for example this is the way :

string hexString = "12968";
uint num = uint.Parse(hexString, System.Globalization.NumberStyles.AllowHexSpecifier);

byte[] floatVals = BitConverter.GetBytes(num);
float f = BitConverter.ToSingle(floatVals, 0);
Console.WriteLine("float convert = {0}", f);

There can be used following to write binary value to registry

static byte[] GetBytes(string str)
{
    byte[] bytes = new byte[str.Length * sizeof(char)];
    System.Buffer.BlockCopy(str.ToCharArray(), 0, bytes, 0, bytes.Length);
    return bytes;
}

RegistryKey rk = Registry.CurrentUser.CreateSubKey("RegistryValueKindExample");
rk.SetValue("BinaryValue", GetBytes("12968"), RegistryValueKind.Binary);

RegistryKey.SetValue Method