Develop Reference

Why do I get a different value after turning an integer into ASCII and then back to an integer?

Why, when I turn INT value to bytes and to ASCII and back, I get another value?
Example:
var asciiStr = new string(Encoding.ASCII.GetChars(BitConverter.GetBytes(2000)));
var intVal = BitConverter.ToInt32(Encoding.ASCII.GetBytes(asciiStr), 0);
Console.WriteLine(intVal);
// Result: 1855

ASCII is only 7-bit - code points above 127 are unsupported. Unsupported characters are converted to ? per the docs on Encoding.ASCII:
The ASCIIEncoding object that is returned by this property might not have the appropriate behavior for your app. It uses replacement fallback to replace each string that it cannot encode and each byte that it cannot decode with a question mark ("?") character.
So 2000 decimal = D0 07 00 00 hexadecimal (little endian) = [unsupported character] [BEL character] [NUL character] [NUL character] = ? [BEL character] [NUL character] [NUL character] = 3F 07 00 00 hexadecimal (little endian) = 1855 decimal.

TL;DR: Everything's fine. But you're a victim of character replacement.
We start with 2000. Let's acknowledge, first, that this number can be represented in hexadecimal as 0x000007d0.
BitConverter.GetBytes
BitConverter.GetBytes(2000) is an array of 4 bytes, Because 2000 is a 32-bit integer literal. So the 32-bit integer representation, in little endian (least significant byte first), is given by the following byte sequence { 0xd0, 0x07, 0x00, 0x00 }. In decimal, those same bytes are { 208, 7, 0, 0 }
Encoding.ASCII.GetChars
Uh oh! Problem. Here's where things likely took an unexpected turn for you.
You're asking the system to interpret those bytes as ASCII-encoded data. The problem is that ASCII uses codes from 0-127. The byte with value 208 (0xd0) doesn't correspond to any character encodable by ASCII. So what actually happens?
When decoding ASCII, if it encounters a byte that is out of the range 0-127 then it decodes that byte to a replacement character and moves to the next byte. This replacement character is a question mark ?. So the 4 chars you get back from Encoding.ASCII.GetChars are ?, BEL (bell), NUL (null) and NUL (null).
BEL is the ASCII name of the character with code 7, which traditionally elicits a beep when presented on a capable terminal. NUL (code 0) is a null character traditionally used for representing the end of a string.
new string
Now you create a string from that array of chars. In C# a string is perfectly capable of representing a NUL character within the body of a string, so your string will have two NUL chars in it. They can be represented in C# string literals with "\0", in case you want to try that yourself. A C# string literal that represents the string you have would be "?\a\0\0" Did you know that the BEL character can be represented with the escape sequence \a? Many people don't.
Encoding.ASCII.GetBytes
Now you begin the reverse journey. Your string is comprised entirely of characters in the ASCII range. The encoding of a question mark is code 63 (0x3F). And the BEL is 7, and the NUL is 0. so the bytes are { 0x3f, 0x07, 0x00, 0x00 }. Surprised? Well, you're encoding a question mark now where before you provided a 208 (0xd0) byte that was not representable with ASCII encoding.
BitConverter.ToInt32
Converting these four bytes back to a 32-bit integer gives the integer 0x0000073f, which, in decimal, is 1855.

String encoding (ASCII, UTF8, SHIFT_JIS, etc.) is designed to pigeonhole human language into a binary (byte) form. It isn't designed to store arbitrary binary data, such as the binary form of an integer.
While your binary data will be interpreted as a string, some of the information will be lost, meaning that storing binary data in this way will fail in the general case. You can see the point where this fails using the following code:
for (int i = 0; i < 255; ++i)
{
var byteData = new byte[] { (byte)i };
var stringData = System.Text.Encoding.ASCII.GetString(byteData);
var encodedAsBytes = System.Text.Encoding.ASCII.GetBytes(stringData);
Console.WriteLine("{0} vs {1}", i, (int)encodedAsBytes[0]);
}
Try it online
As you can see it starts off well because all of the character codes correspond to ASCII characters, but once we get up in the numbers (i.e. 128 and beyond), we start to require a more than 7 bits to store the binary value. At this point it ceases to be decoded correctly, and we start seeing 63 come back instead of the input value.
Ultimately you will have this problem encoding binary data using any string encoding. You need to choose an encoding method specifically meant for storing binary data as a string.
Two popular methods are:
Hexadecimal
Base64 using ToBase64String and FromBase64String
Hexadecimal example (using the hex methods here):
int initialValue = 2000;
Console.WriteLine(initialValue);
// Convert from int to bytes and then to hex
byte[] bytesValue = BitConverter.GetBytes(initialValue);
string stringValue = ByteArrayToString(bytesValue);
Console.WriteLine("As hex: {0}", stringValue); // outputs D0070000
// Convert form hex to bytes and then to int
byte[] decodedBytesValue = StringToByteArray(stringValue);
int intValue = BitConverter.ToInt32(decodedBytesValue, 0);
Console.WriteLine(intValue);
Try it online
Base64 example:
int initialValue = 2000;
Console.WriteLine(initialValue);
// Convert from int to bytes and then to base64
byte[] bytesValue = BitConverter.GetBytes(initialValue);
string stringValue = Convert.ToBase64String(bytesValue);
Console.WriteLine("As base64: {0}", stringValue); // outputs 0AcAAA==
// Convert form base64 to bytes and then to int
byte[] decodedBytesValue = Convert.FromBase64String(stringValue);
int intValue = BitConverter.ToInt32(decodedBytesValue, 0);
Console.WriteLine(intValue);
Try it online
P.S. If you simply wanted to convert your integer to a string (e.g. "2000") then you can simply use .ToString():
int initialValue = 2000;
string stringValue = initialValue.ToString();

How to convert From Hex To Dump in C#

I convert my Hex to dump to get special character like symbol but when I try to convert my "0x18" i "\u0018" this value. Can anyone give me solution regarding this matter.
Here is my code:
public static string FromHexDump(string sText)
{
Int32 lIdx;
string prValue ="" ;
for (lIdx = 1; lIdx < sText.Length; lIdx += 2)
{
string prString = "0x" + Mid(sText, lIdx, 2);
string prUniCode = Convert.ToChar(Convert.ToInt64(prString,16)).ToString();
prValue = prValue + prUniCode;
}
return prValue;
}
I used VB language. I have a database that already encrypted text to my password and the value is BAA37D40186D like this so I loop it by step 2 and it will like this 0xBA,0xA3,0x7D,0x40,0x18,0x6D and the VB result getting like this º£}#m

You can use this code:
var myHex = '\x0633';
var formattedString += string.Format(#"\x{0:x4}", (int)myHex);
Or you can use this code from MSDN (https://learn.microsoft.com/en-us/dotnet/csharp/programming-guide/types/how-to-convert-between-hexadecimal-strings-and-numeric-types):
string hexValues = "48 65 6C 6C 6F 20 57 6F 72 6C 64 21";
string[] hexValuesSplit = hexValues.Split(' ');
foreach (string hex in hexValuesSplit)
{
// Convert the number expressed in base-16 to an integer.
int value = Convert.ToInt32(hex, 16);
// Get the character corresponding to the integral value.
string stringValue = Char.ConvertFromUtf32(value);
char charValue = (char)value;
Console.WriteLine("hexadecimal value = {0}, int value = {1}, char value = {2} or {3}",
hex, value, stringValue, charValue);
}

The question is unclear - what is the database column's type? Does it contain 6 bytes, or 12 characters with the hex encoding of the bytes? In any case, this has nothing to do with special characters or encodings.
First, 0x18 is the byte value of the Cancel Character in the Latin 1 codepage, not the pound sign. That's 0xA3. It seems that the byte values in the question are just the Latin 1 bytes for the string in hex.
.NET strings are Unicode (UTF16LE specifically). There's no UTF8 string or Latin1 string. Encodings and codepages apply when converting bytes to strings or vice versa. This is done using the Encoding class and eg Encoding.GetBytes
In this case, this code will convert the byte to the expected string form, including the unprintable character :
new byte[] {0xBA,0xA3,0x7D,0x40,0x18,0x6D};
var latinEncoding=Encoding.GetEncoding(1252);
var result=latinEncoding.GetString(dbBytes);
The result is :
º£}#m
With the Cancel character between # and m.
If the database column contains the byte values as strings :
it takes double the required space and
the hex values have to be converted back to bytes before converting to strings
The x format is used to convert numbers or bytes to their hex form and vice versa. For each byte value, ToString("x") returns the hex string.
The hex string can be produced from the original buffer with :
var dbBytes=new byte[] {0xBA,0xA3,0x7D,0x40,0x18,0x6D};
var hexString=String.Join("",dbBytes.Select(c=>c.ToString("x")));
There are many questions that show how to parse a byte string into a byte array. I'll just steal Jared Parson's LINQ answer :
public static byte[] StringToByteArray(string hex) {
return Enumerable.Range(0, hex.Length)
.Where(x => x % 2 == 0)
.Select(x => Convert.ToByte(hex.Substring(x, 2), 16))
.ToArray();
}
With that, we can parse the hex string into a byte array and convert it to the original string :
var bytes=StringToByteArray(hexString);
var latinEncoding=Encoding.GetEncoding(1252);
var result=latinEncoding.GetString(bytes);

First of all u don't need dump but Unicode, I would recomend to read about unicode/encoding etc and why this is a problem with strings.
PS: solution : StackOverflow

Convert from Hexadecimal to Text

With respect to this tool, I need to convert hexadecimal data, irrespective of their combination to equivalent text. For example:
"HelloWorld" = 48656c6c6f576f726c64;
The solution needs to take into account that hexadecimal can be grouped in different lengths:
48656c6c 6f576f72 6c64
or
48 65 6c 6c 6f 57 6f 72 6c 64
All of the hexadecimal values supplied above read as HelloWorld when converted to text.

First, I would like to point out that this question has been asked many times on the web (here is one example). However, I am going to break this down step by step for you to hopefully teach you how to not only utilize your resources available on the web, but also how to solve your problem.
Overview: Converting from hexadecimal data to text that is able to be read by human beings is a straight-forward process in modern development languages; you clean the data (ensuring no illegal characters remain), then you convert down to the byte level so that you can work with the raw data. Finally, you'll convert that raw data into readable text utilizing a method that has already been created by Microsoft.
Important: Remember, for the conversion to work, you have to ensure you're converting in the same format that you started with:
ASCII -> ASCII: Works Great!
ASCII -> UTF7: Not so much...
Removing Illegal Characters: One of the first things you'll need to do is ensure the hexadecimal value that you're supplying doesn't contain any illegal characters. The simplest way to do this is to create an array of acceptable characters and then remove anything but these in a loop:
private string GetCleanHex(string hex) {
string legalCharacters = "0123456789ABCDEF";
string result = hex.ToUpper();
foreach (char c in result) {
if (!legalCharacters.Contains(c))
result = result.Replace(c.ToString(), string.Empty);
}
}
Getting The Byte Array: Once you've cleaned out all illegal characters, you can now convert your hexadecimal string into a byte array. This is required to convert from hexadecimal to ASCII. This step was provided by the linked post above:
private byte[] GetBytesFromHex(string hex) {
byte[] bytes = new byte[result.Length / 2];
for (int i = 0; i < bytes.Length; i++)
bytes[i] = Convert.ToByte(result.Substring(i * 2, 2), 16);
}
Converting To Text: Now that you've cleaned your data, and converted it to a byte[], you can now convert that byte data into ASCII. This can be done using a method available in Encoding.ASCII called GetString:
string text = Encoding.ASCII.GetString(bytes);
The Final Result: Plug all of this into your application and you'll have successfully converted hexadecimal data into clean, readable text:
string hex = GetCleanHex("506c 65 61736520 72 656164 20686f77 2074 6f 2061 73 6b 2e");
byte[] bytes = GetBytesFromHex(hex);
string text = Encoding.ASCII.GetString(bytes);
Console.WriteLine(text);
Console.ReadKey();
The code above will print the following text to the console:
Please read how to ask.

C# Encoding.Default.GetBytes() method and Integer representation

I saw this code example:
using (FileStream fStream = File.Open(#"C:\myMessage.dat", FileMode.Create))
{
string msg = "Helloo";
byte[] msgAsByteArray = Encoding.Default.GetBytes(msg);
foreach (var a in msgAsByteArray)
{
Console.WriteLine($"a: {a}");
}
// Write byte[] to file.
fStream.Write(msgAsByteArray, 0, msgAsByteArray.Length);
// Reset internal position of stream.
fStream.Position = 0;
// Read the types from file and display to console.
Console.Write("Your message as an array of bytes: ");
byte[] bytesFromFile = new byte[msgAsByteArray.Length];
for (int i = 0; i < msgAsByteArray.Length; i++)
{
bytesFromFile[i] = (byte)fStream.ReadByte();
Console.Write(bytesFromFile[i]);
}
// Display decoded messages.
Console.Write("\nDecoded Message: ");
Console.WriteLine(Encoding.Default.GetString(bytesFromFile));
And the result of Console.WriteLine($"a: {a}") is this:
a: 72
a: 101
a: 108
a: 108
a: 111
a: 111
1.
I thought byte[] is composed of many each unit of byte.
But each byte is represented in integer number.
That numbers must be corresponding ASCII characters.
In C#, byte array means data represented in ASCII?
2.
Is the file myMessage.dat composed of binary data composed of only 0 and 1?
But when I open myMessage.dat with the text editor, it's showing Helloo text string. What's the reason for this?

A byte is a 8bit integer with values from 0 to 255. The output to console outputs the normal number, by providing a format string (https://learn.microsoft.com/en-us/dotnet/standard/base-types/standard-numeric-format-strings) you can output as hex. You can use this answer to get the binary representation.
You explicitly converted the "Halloo" to bytes with Encoding.Default.GetBytes() - that is kindof like converting it to its ascii value but heeding the default encoding on your system.
Your texteditor interpretes the data of the file and displays it as it can. If you put a byte[] myBytes = new [] {0,7,12,3,9,30} into a file and open that with your textedit you will get nonreadable texts as "normal text" starts around 32 , before are f.e. tabs, bells, line feeds and other special non printable characters. See f.e. NonPrintableAscii

C# Ascii to bytes, parsing not conversion

I have a windows form where you can input text in one textbox, and it outputs the conversion in the other textbox. I have various conversions.
say I input "hello world"
my ascii to bytes function gives me back: 10410110810811132119111114108100
all is good. now I need to use my bytes to ascii function to convert it back.
the problem is that
byte[] b;
b = ASCIIEncoding.ASCII.GetBytes(plaintext); //it is a string from the textbox
OK, MOSTLY SOLVED, BUT, the problem still remains, input "1101000 1100101" as a string, parse as bytes/ byte array, and then get a string out of it. (I know the last part)

UPDATE
From binary input string to ASCII string
using System;
using System.Linq;
public class Program
{
public static void Main()
{
string input = "1101000 1100101 1101100 1101100 1101111 100000 1110111 1101111 1110010 1101100 1100100";
string[] binary = input.Split(' ');
Console.WriteLine(String.Join("", binary.Select(b => Convert.ToChar(Convert.ToByte(b, 2))).ToArray()));
}
}
Results:
hello world
Demo
OLD ANSWER
So now it sounds like you want to convert your string to binary and then from binary back to a string. From my OLD ANSWER, you can use the Select() (LINQ) statement to convert your string to a binary string array.
Once you have a binary string array, to convert it back you have to convert each element to a byte from base 2, then convert the byte to a char resulting in a char[], from which can be converting back to a string. No padding is necessary.
using System;
using System.Linq;
using System.Text;
public class Program
{
public static void Main()
{
string input = "hello world";
byte[] inputBytes = ASCIIEncoding.ASCII.GetBytes(input);
// Decimal display
Console.WriteLine(String.Join(" ", inputBytes));
// Hex display
Console.WriteLine(String.Join(" ", inputBytes.Select(ib => ib.ToString("X2"))));
// Binary display
string[] binary = inputBytes.Select(ib => Convert.ToString(ib, 2)).ToArray();
Console.WriteLine(String.Join(" ", binary));
// Converting bytes back to string
Console.WriteLine(ASCIIEncoding.ASCII.GetString(inputBytes, 0, inputBytes.Length));
// Binary to ASCII (This is what you're looking for)
Console.WriteLine(String.Join("", binary.Select(b => Convert.ToChar(Convert.ToByte(b, 2)))));
}
}
Results:
104 101 108 108 111 32 119 111 114 108 100
68 65 6C 6C 6F 20 77 6F 72 6C 64
1101000 1100101 1101100 1101100 1101111 100000 1110111 1101111 1110010 1101100 1100100
hello world
hello world
Demo

The inverse to ASCIIEncoding.ASCII.GetBytes(string) is ASCIIEncoding.ASCII.GetString(bytes[]):
string plaintext = "hello world";
byte[] b = ASCIIEncoding.ASCII.GetBytes(plaintext);
Console.WriteLine(b); // new bytes[] { 104, 101, 108, 108, 111, 32, 119, 111, 114, 108, 100 }
string s = ASCIIEncoding.ASCII.GetString(b);
Console.WriteLine(s); // "hello world"
how the heck does ASCIIEncoding.ASCII.GetBytes("hello world") give me back 10410110810811132119111114108100?! that's not binary!
It does not give you that number. It gives you a byte array; an array of bytes. And a byte is a number between 0 and 255 (which can be stored in one byte, hence them name). What did you expect? A string containing only 1 and 0 characters? That’s not binary either; that’s a string.
You can use Convert.ToString to get a binary string from a single byte:
Console.WriteLine(Convert.ToString(104, 2)); // "1101000"
Note that you need to left-pad those strings to make them use 8 characters.