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System.Byte struct

  • Article

This article provides supplementary remarks to the reference documentation for this API.

Byte is an immutable value type that represents unsigned integers with values that range from 0 (which is represented by the Byte.MinValue constant) to 255 (which is represented by the Byte.MaxValue constant). .NET also includes a signed 8-bit integer value type, SByte, which represents values that range from -128 to 127.

Instantiate a Byte value

You can instantiate a Byte value in several ways:

  • You can declare a Byte variable and assign it a literal integer value that is within the range of the Byte data type. The following example declares two Byte variables and assigns them values in this way.

    byte value1 = 64;
byte value2 = 255;

    let value1 = 64uy
let value2 = 255uy

    Dim value1 As Byte = 64
Dim value2 As Byte = 255

  • You can assign a non-byte numeric value to a byte. This is a narrowing conversion, so it requires a cast operator in C# and F#, or a conversion method in Visual Basic if Option Strict is on. If the non-byte value is a Single, Double, or Decimal value that includes a fractional component, the handling of its fractional part depends on the compiler performing the conversion. The following example assigns several numeric values to Byte variables.

    int int1 = 128;
try
{
    byte value1 = (byte)int1;
    Console.WriteLine(value1);
}
catch (OverflowException)
{
    Console.WriteLine("{0} is out of range of a byte.", int1);
}

double dbl2 = 3.997;
try
{
    byte value2 = (byte)dbl2;
    Console.WriteLine(value2);
}
catch (OverflowException)
{
    Console.WriteLine("{0} is out of range of a byte.", dbl2);
}
// The example displays the following output:
//       128
//       3

    let int1 = 128
try
    let value1 = byte int1
    printfn $"{value1}"
with :? OverflowException ->
    printfn $"{int1} is out of range of a byte."

let dbl2 = 3.997
try
    let value2 = byte dbl2
    printfn $"{value2}"
with :? OverflowException ->
    printfn $"{dbl2} is out of range of a byte."

// The example displays the following output:
//       128
//       3

    Dim int1 As Integer = 128
Try
    Dim value1 As Byte = CByte(int1)
    Console.WriteLine(value1)
Catch e As OverflowException
    Console.WriteLine("{0} is out of range of a byte.", int1)
End Try

Dim dbl2 As Double = 3.997
Try
    Dim value2 As Byte = CByte(dbl2)
    Console.WriteLine(value2)
Catch e As OverflowException
    Console.WriteLine("{0} is out of range of a byte.", dbl2)
End Try
' The example displays the following output:
'       128
'       4

  • You can call a method of the Convert class to convert any supported type to a Byte value. This is possible because Byte supports the IConvertible interface. The following example illustrates the conversion of an array of Int32 values to Byte values.

    int[] numbers = { Int32.MinValue, -1, 0, 121, 340, Int32.MaxValue };
byte result;
foreach (int number in numbers)
{
    try
    {
        result = Convert.ToByte(number);
        Console.WriteLine("Converted the {0} value {1} to the {2} value {3}.",
                          number.GetType().Name, number,
                          result.GetType().Name, result);
    }
    catch (OverflowException)
    {
        Console.WriteLine("The {0} value {1} is outside the range of the Byte type.",
                          number.GetType().Name, number);
    }
}
// The example displays the following output:
//       The Int32 value -2147483648 is outside the range of the Byte type.
//       The Int32 value -1 is outside the range of the Byte type.
//       Converted the Int32 value 0 to the Byte value 0.
//       Converted the Int32 value 121 to the Byte value 121.
//       The Int32 value 340 is outside the range of the Byte type.
//       The Int32 value 2147483647 is outside the range of the Byte type.

    let numbers = [| Int32.MinValue; -1; 0; 121; 340; Int32.MaxValue |]
for number in numbers do
    try
        let result = Convert.ToByte number
        printfn $"Converted the {number.GetType().Name} value {number} to the {result.GetType().Name} value {result}."
    with :? OverflowException ->
        printfn $"The {number.GetType().Name} value {number} is outside the range of the Byte type."
// The example displays the following output:
//       The Int32 value -2147483648 is outside the range of the Byte type.
//       The Int32 value -1 is outside the range of the Byte type.
//       Converted the Int32 value 0 to the Byte value 0.
//       Converted the Int32 value 121 to the Byte value 121.
//       The Int32 value 340 is outside the range of the Byte type.
//       The Int32 value 2147483647 is outside the range of the Byte type.

    Dim numbers() As Integer = {Int32.MinValue, -1, 0, 121, 340, Int32.MaxValue}
Dim result As Byte
For Each number As Integer In numbers
    Try
        result = Convert.ToByte(number)
        Console.WriteLine("Converted the {0} value {1} to the {2} value {3}.",
                      number.GetType().Name, number,
                      result.GetType().Name, result)
    Catch e As OverflowException
        Console.WriteLine("The {0} value {1} is outside the range of the Byte type.",
                      number.GetType().Name, number)
    End Try
Next
' The example displays the following output:
'       The Int32 value -2147483648 is outside the range of the Byte type.
'       The Int32 value -1 is outside the range of the Byte type.
'       Converted the Int32 value 0 to the Byte value 0.
'       Converted the Int32 value 121 to the Byte value 121.
'       The Int32 value 340 is outside the range of the Byte type.
'       The Int32 value 2147483647 is outside the range of the Byte type.

  • You can call the Parse or TryParse method to convert the string representation of a Byte value to a Byte. The string can contain either decimal or hexadecimal digits. The following example illustrates the parse operation by using both a decimal and a hexadecimal string.

    string string1 = "244";
try
{
    byte byte1 = Byte.Parse(string1);
    Console.WriteLine(byte1);
}
catch (OverflowException)
{
    Console.WriteLine("'{0}' is out of range of a byte.", string1);
}
catch (FormatException)
{
    Console.WriteLine("'{0}' is out of range of a byte.", string1);
}

string string2 = "F9";
try
{
    byte byte2 = Byte.Parse(string2,
                            System.Globalization.NumberStyles.HexNumber);
    Console.WriteLine(byte2);
}
catch (OverflowException)
{
    Console.WriteLine("'{0}' is out of range of a byte.", string2);
}
catch (FormatException)
{
    Console.WriteLine("'{0}' is out of range of a byte.", string2);
}
// The example displays the following output:
//       244
//       249

    let string1 = "244"
try
    let byte1 = Byte.Parse string1
    printfn $"{byte1}" 
with
| :? OverflowException ->
    printfn $"'{string1}' is out of range of a byte."
| :? FormatException ->
    printfn $"'{string1}' is out of range of a byte."

let string2 = "F9"
try
    let byte2 = Byte.Parse(string2, System.Globalization.NumberStyles.HexNumber)
    printfn $"{byte2}"
with
| :? OverflowException ->
    printfn $"'{string2}' is out of range of a byte."
| :? FormatException ->
    printfn $"'{string2}' is out of range of a byte."

// The example displays the following output:
//       244
//       249

    Dim string1 As String = "244"
Try
    Dim byte1 As Byte = Byte.Parse(string1)
    Console.WriteLine(byte1)
Catch e As OverflowException
    Console.WriteLine("'{0}' is out of range of a byte.", string1)
Catch e As FormatException
    Console.WriteLine("'{0}' is out of range of a byte.", string1)
End Try

Dim string2 As String = "F9"
Try
    Dim byte2 As Byte = Byte.Parse(string2,
                           System.Globalization.NumberStyles.HexNumber)
    Console.WriteLine(byte2)
Catch e As OverflowException
    Console.WriteLine("'{0}' is out of range of a byte.", string2)
Catch e As FormatException
    Console.WriteLine("'{0}' is out of range of a byte.", string2)
End Try
' The example displays the following output:
'       244
'       249

Perform operations on Byte values

The Byte type supports standard mathematical operations such as addition, subtraction, division, multiplication, subtraction, negation, and unary negation. Like the other integral types, the Byte type also supports the bitwise AND, OR, XOR, left shift, and right shift operators.

You can use the standard numeric operators to compare two Byte values, or you can call the CompareTo or Equals method.

You can also call the members of the Math class to perform a wide range of numeric operations, including getting the absolute value of a number, calculating the quotient and remainder from integral division, determining the maximum or minimum value of two integers, getting the sign of a number, and rounding a number.

Represent a Byte as a String

The Byte type provides full support for standard and custom numeric format strings. (For more information, see Formatting Types, Standard Numeric Format Strings, and Custom Numeric Format Strings.) However, most commonly, byte values are represented as one-digit to three-digit values without any additional formatting, or as two-digit hexadecimal values.

To format a Byte value as an integral string with no leading zeros, you can call the parameterless ToString() method. By using the "D" format specifier, you can also include a specified number of leading zeros in the string representation. By using the "X" format specifier, you can represent a Byte value as a hexadecimal string. The following example formats the elements in an array of Byte values in these three ways.

byte[] numbers = { 0, 16, 104, 213 };
foreach (byte number in numbers)
{
    // Display value using default formatting.
    Console.Write("{0,-3}  -->   ", number.ToString());
    // Display value with 3 digits and leading zeros.
    Console.Write(number.ToString("D3") + "   ");
    // Display value with hexadecimal.
    Console.Write(number.ToString("X2") + "   ");
    // Display value with four hexadecimal digits.
    Console.WriteLine(number.ToString("X4"));
}
// The example displays the following output:
//       0    -->   000   00   0000
//       16   -->   016   10   0010
//       104  -->   104   68   0068
//       213  -->   213   D5   00D5

let numbers = [| 0; 16; 104; 213 |]
for number in numbers do
    // Display value using default formatting.
    number.ToString()
    |> printf "%-3s  -->   "

    // Display value with 3 digits and leading zeros.
    number.ToString "D3"
    |> printf "%s   "
    
    // Display value with hexadecimal.
    number.ToString "X2"
    |> printf "%s   "
    
    // Display value with four hexadecimal digits.
    number.ToString "X4"
    |> printfn "%s"

// The example displays the following output:
//       0    -->   000   00   0000
//       16   -->   016   10   0010
//       104  -->   104   68   0068
//       213  -->   213   D5   00D5

Dim numbers() As Byte = {0, 16, 104, 213}
For Each number As Byte In numbers
    ' Display value using default formatting.
    Console.Write("{0,-3}  -->   ", number.ToString())
    ' Display value with 3 digits and leading zeros.
    Console.Write(number.ToString("D3") + "   ")
    ' Display value with hexadecimal.
    Console.Write(number.ToString("X2") + "   ")
    ' Display value with four hexadecimal digits.
    Console.WriteLine(number.ToString("X4"))
Next
' The example displays the following output:
'       0    -->   000   00   0000
'       16   -->   016   10   0010
'       104  -->   104   68   0068
'       213  -->   213   D5   00D5

You can also format a Byte value as a binary, octal, decimal, or hexadecimal string by calling the ToString(Byte, Int32) method and supplying the base as the method's second parameter. The following example calls this method to display the binary, octal, and hexadecimal representations of an array of byte values.

byte[] numbers = { 0, 16, 104, 213 };
Console.WriteLine("{0}   {1,8}   {2,5}   {3,5}",
                  "Value", "Binary", "Octal", "Hex");
foreach (byte number in numbers)
{
    Console.WriteLine("{0,5}   {1,8}   {2,5}   {3,5}",
                      number, Convert.ToString(number, 2),
                      Convert.ToString(number, 8),
                      Convert.ToString(number, 16));
}
// The example displays the following output:
//       Value     Binary   Octal     Hex
//           0          0       0       0
//          16      10000      20      10
//         104    1101000     150      68
//         213   11010101     325      d5

let numbers = [| 0; 16; 104; 213 |]
printfn "%s   %8s   %5s   %5s" "Value" "Binary" "Octal" "Hex"
for number in numbers do
    printfn $"%5i{number}   %8s{Convert.ToString(number, 2)}   %5s{Convert.ToString(number, 8)}   %5s{Convert.ToString(number, 16)}"
                    
// The example displays the following output:
//       Value     Binary   Octal     Hex
//           0          0       0       0
//          16      10000      20      10
//         104    1101000     150      68
//         213   11010101     325      d5

Dim numbers() As Byte = {0, 16, 104, 213}
Console.WriteLine("{0}   {1,8}   {2,5}   {3,5}",
                "Value", "Binary", "Octal", "Hex")
For Each number As Byte In numbers
    Console.WriteLine("{0,5}   {1,8}   {2,5}   {3,5}",
                   number, Convert.ToString(number, 2),
                   Convert.ToString(number, 8),
                   Convert.ToString(number, 16))
Next
' The example displays the following output:
'       Value     Binary   Octal     Hex
'           0          0       0       0
'          16      10000      20      10
'         104    1101000     150      68
'         213   11010101     325      d5

Work with non-decimal Byte values

In addition to working with individual bytes as decimal values, you may want to perform bitwise operations with byte values, or work with byte arrays or with the binary or hexadecimal representations of byte values. For example, overloads of the BitConverter.GetBytes method can convert each of the primitive data types to a byte array, and the BigInteger.ToByteArray method converts a BigInteger value to a byte array.

Byte values are represented in 8 bits by their magnitude only, without a sign bit. This is important to keep in mind when you perform bitwise operations on Byte values or when you work with individual bits. To perform a numeric, Boolean, or comparison operation on any two non-decimal values, both values must use the same representation.

When an operation is performed on two Byte values, the values share the same representation, so the result is accurate. This is illustrated in the following example, which masks the lowest-order bit of a Byte value to ensure that it is even.

using System;
using System.Globalization;

public class Example
{
   public static void Main()
   {
      string[] values = { Convert.ToString(12, 16),
                          Convert.ToString(123, 16),
                          Convert.ToString(245, 16) };

      byte mask = 0xFE;
      foreach (string value in values) {
         Byte byteValue = Byte.Parse(value, NumberStyles.AllowHexSpecifier);
         Console.WriteLine("{0} And {1} = {2}", byteValue, mask,
                           byteValue & mask);
      }
   }
}
// The example displays the following output:
//       12 And 254 = 12
//       123 And 254 = 122
//       245 And 254 = 244

open System
open System.Globalization

let values = 
    [ Convert.ToString(12, 16)
      Convert.ToString(123, 16)
      Convert.ToString(245, 16) ]

let mask = 0xFEuy
for value in values do
    let byteValue = Byte.Parse(value, NumberStyles.AllowHexSpecifier)
    printfn $"{byteValue} And {mask} = {byteValue &&& mask}"
                    

// The example displays the following output:
//       12 And 254 = 12
//       123 And 254 = 122
//       245 And 254 = 244

Imports System.Globalization

Module Example1
    Public Sub Main()
        Dim values() As String = {Convert.ToString(12, 16),
                                 Convert.ToString(123, 16),
                                 Convert.ToString(245, 16)}

        Dim mask As Byte = &HFE
        For Each value As String In values
            Dim byteValue As Byte = Byte.Parse(value, NumberStyles.AllowHexSpecifier)
            Console.WriteLine("{0} And {1} = {2}", byteValue, mask,
                           byteValue And mask)
        Next
    End Sub
End Module
' The example displays the following output:
'       12 And 254 = 12
'       123 And 254 = 122
'       245 And 254 = 244

On the other hand, when you work with both unsigned and signed bits, bitwise operations are complicated by the fact that the SByte values use sign-and-magnitude representation for positive values, and two's complement representation for negative values. In order to perform a meaningful bitwise operation, the values must be converted to two equivalent representations, and information about the sign bit must be preserved. The following example does this to mask out bits 2 and 4 of an array of 8-bit signed and unsigned values.

using System;
using System.Collections.Generic;
using System.Globalization;

public struct ByteString
{
    public string Value;
    public int Sign;
}

public class Example1
{
    public static void Main()
    {
        ByteString[] values = CreateArray(-15, 123, 245);

        byte mask = 0x14;        // Mask all bits but 2 and 4.

        foreach (ByteString strValue in values)
        {
            byte byteValue = Byte.Parse(strValue.Value, NumberStyles.AllowHexSpecifier);
            Console.WriteLine("{0} ({1}) And {2} ({3}) = {4} ({5})",
                              strValue.Sign * byteValue,
                              Convert.ToString(byteValue, 2),
                              mask, Convert.ToString(mask, 2),
                              (strValue.Sign & Math.Sign(mask)) * (byteValue & mask),
                              Convert.ToString(byteValue & mask, 2));
        }
    }

    private static ByteString[] CreateArray(params int[] values)
    {
        List<ByteString> byteStrings = new List<ByteString>();

        foreach (object value in values)
        {
            ByteString temp = new ByteString();
            int sign = Math.Sign((int)value);
            temp.Sign = sign;

            // Change two's complement to magnitude-only representation.
            temp.Value = Convert.ToString(((int)value) * sign, 16);

            byteStrings.Add(temp);
        }
        return byteStrings.ToArray();
    }
}
// The example displays the following output:
//       -15 (1111) And 20 (10100) = 4 (100)
//       123 (1111011) And 20 (10100) = 16 (10000)
//       245 (11110101) And 20 (10100) = 20 (10100)

open System
open System.Collections.Generic
open System.Globalization

[<Struct>]
type ByteString =
    { Sign: int
      Value: string }

let createArray values =
    [ for value in values do
        let sign = sign value
        { Sign = sign
         // Change two's complement to magnitude-only representation.
          Value = Convert.ToString(value * sign, 16)} ]


let values = createArray [ -15; 123; 245 ]

let mask = 0x14uy        // Mask all bits but 2 and 4.

for strValue in values do
    let byteValue = Byte.Parse(strValue.Value, NumberStyles.AllowHexSpecifier)
    printfn $"{strValue.Sign * int byteValue} ({Convert.ToString(byteValue, 2)}) And {mask} ({Convert.ToString(mask, 2)}) = {(strValue.Sign &&& (int mask |> sign)) * int (byteValue &&& mask)} ({Convert.ToString(byteValue &&& mask, 2)})"

// The example displays the following output:
//       -15 (1111) And 20 (10100) = 4 (100)
//       123 (1111011) And 20 (10100) = 16 (10000)
//       245 (11110101) And 20 (10100) = 20 (10100)

Imports System.Collections.Generic
Imports System.Globalization

Public Structure ByteString
   Public Value As String
   Public Sign As Integer
End Structure

Module Example2
    Public Sub Main()
        Dim values() As ByteString = CreateArray(-15, 123, 245)

        Dim mask As Byte = &H14        ' Mask all bits but 2 and 4.

        For Each strValue As ByteString In values
            Dim byteValue As Byte = Byte.Parse(strValue.Value, NumberStyles.AllowHexSpecifier)
            Console.WriteLine("{0} ({1}) And {2} ({3}) = {4} ({5})",
                           strValue.Sign * byteValue,
                           Convert.ToString(byteValue, 2),
                           mask, Convert.ToString(mask, 2),
                           (strValue.Sign And Math.Sign(mask)) * (byteValue And mask),
                           Convert.ToString(byteValue And mask, 2))
        Next
    End Sub

    Private Function CreateArray(ParamArray values() As Object) As ByteString()
        Dim byteStrings As New List(Of ByteString)
        For Each value As Object In values
            Dim temp As New ByteString()
            Dim sign As Integer = Math.Sign(value)
            temp.Sign = sign
            ' Change two's complement to magnitude-only representation.
            value = value * sign

            temp.Value = Convert.ToString(value, 16)
            byteStrings.Add(temp)
        Next
        Return byteStrings.ToArray()
    End Function
End Module
' The example displays the following output:
'       -15 (1111) And 20 (10100) = 4 (100)
'       123 (1111011) And 20 (10100) = 16 (10000)
'       245 (11110101) And 20 (10100) = 20 (10100)