I've a List with either 1, 2 or 4 hex values saved as decimal values. I want to convert them into one decimal number.
Example:
List<Byte> values: 1 and 95 (= 0x01, 0x5F)
I want to convert the list into one decimal number: 0x015F = 351
How can I do that?
var result = 0;
var i = 0;
foreach (var val in values)
{
result = (result << i) + (int)val;
i += 8;
}
int (System.Int32), so will not work for a List<byte> with more than four entries. You can use long/ulong, or BigInteger, instead of int, for the result variable. Just change the first line to BigInteger result = 0;.Modern, LINQ-based way (old-fashined C-programmers can turn in one's grave):
List<Byte> list = new List<byte>() { 0x01, 0x5F };
var output = list.Select(x => (int)x)
.Reverse()
.Aggregate((x, y) => (int)0x100 * y + (int)x);
With BitConverter class, you can do:
var values = new List<byte> { 0x01, 0x5F, };
byte[] arr = new byte[4];
for (int i = 0; i < values.Count; ++i)
arr[values.Count - 1 - i] = values[i];
int result = BitConverter.ToInt32(arr, 0);
You fill the array arr backwards from the middle, as seen.
If the numbers can be greater (i.e. the List<> can be up to 8 bytes long), use ulong (never negative), for example:
var values = new List<byte> { 0x01, 0x5F, };
byte[] arr = new byte[8];
for (int i = 0; i < values.Count; ++i)
arr[values.Count - 1 - i] = values[i];
ulong result = BitConverter.ToUInt64(arr, 0);
If the List<> can be arbitrarily long, use new BigInteger(arr) (requires csproj reference to System.Numerics.dll assembly).
015Fstring or 351 in decimal?