I have a string that I receive from a third party app and I would like to display it correctly in any language using C# on my Windows Surface.
Due to incorrect encoding, a piece of my string looks like this in Farsi (Persian-Arabic):
مدل-رنگ-موی-جدید-5-436x500
whereas it should look like this:
مدل-رنگ-موی-جدید-5-436x500
This link convert this correctly:
http://www.ltg.ed.ac.uk/~richard/utf-8.html
How I can do it in c#?
It is very hard to tell exactly what is going on from the description of your question. We would all be much better off if you provided us with an example of what is happening using a single character instead of a whole string, and if you chose an example character which does not belong to some exotic character set, for example the bullet character (u2022) or something like that.
Anyhow, what is probably happening is this:
The letter "ر" is represented in UTF-8 as a byte sequence of D8 B1, but what you see is "ر", and that's because in UTF-16 Ø is u00D8 and ± is u00B1. So, the incoming text was originally in UTF-8, but in the process of importing it to a dotNet Unicode String in your application it was incorrectly interpreted as being in some 8-bit character set such as ANSI or Latin-1. That's why you now have a Unicode String which appears to contain garbage.
However, the process of converting 8-bit characters to Unicode is for the most part not destructive, so all of the information is still there, that's why the UTF-8 tool that you linked to can still kind of make sense out of it.
What you need to do is convert the string back to an array of ANSI (or Latin-1, whatever) bytes, and then re-construct the string the right way, which is a conversion of UTF-8 to Unicode.
I cannot easily reproduce your situation, so here are some things to try:
byte[] bytes = System.Text.Encoding.Ansi.GetBytes( garbledUnicodeString );
followed by
string properUnicodeString = System.Text.Encoding.UTF8.GetString( bytes );
Related
Below is what the text looks like when viewed in NotePad++.
I need to get the IndexOf for that peice of the string. for use the the below code. And I can't figure out how to use the odd characters in my code.
int start = text.IndexOf("AppxxxxxxDB INFO");
Where the "xxxxx"'s represent the strange characters.
All these characters have corresponding ASCII codes, you can insert them in a string by escaping it.
For instance:
"App\x0000\x0001\x0000\x0003\x0000\x0000\x0000DB INFO"
or shorter:
"App\x00\x01\x00\x03\x00\x00\x00"+"DB INFO"
\xXXXX means you specify one character with XXXX the hexadecimal number corresponding to the character.
Notepad++ simply wants to make it a bit more convenient by rendering these characters by printing the abbreviation in a "bubble". But that's just rendering.
The origin of these characters is printer (and other media) directives. For instance you needed to instruct a printer to move to the next line, stop the printing job, nowadays they are still used. Some terminals use them to communicate color changes, etc. The most well known is \n or \x000A which means you start a new line. For text they are thus characters that specify how to handle text. A bit equivalent to modern html, etc. (although it's only a limited equivalence). \n is thus only a new line because there is a consensus about that. If one defines his/her own encoding, he can invent a new system.
Echoing #JonSkeet's warning, when you read a file into a string, the file's bytes are decoded according to a character set encoding. The decoder has to do something with bytes values or sequences that are invalid per the encoding rules. Typical decoders substitute a replacement character and attempt to go on.
I call that data corruption. In most cases, I'd rather have the decoder throw an exception.
You can use a standard decoder, customize one or create a new one with the Encoding class to get the behavior you want. Or, you can preserve the original bytes by reading the file as bytes instead of as text.
If you insist on reading the file as text, I suggest using the 437 encoding because it has 256 characters, one for every byte value, no restrictions on byte sequences and each 437 character is also in Unicode. The bytes that represent text will possibly decode the same characters that you want to search for as strings, but you have to check, comparing 437 and Unicode in this table.
Really, you should have and follow the specification for the file type you are reading. After all, there is no text but encoded text, and you have to know which encoding it is.
I am having some issues with the default string encoding in C#. I need to read strings from certain files/packets. However, these strings include characters from the 128-256 range (extended ascii), and all of these characters show up as question marks , instead of the proper character. For example, when reading a string ,it could come up as "S?meStr?n?" if the string contained the extended ascii characters.
Now, is there any way to change the default encoding for my application? I know in java you could define the default character set from command line.
There's no one single "extended ASCII" encoding. There are lots of different 8-bit encodings which are compatible with ASCII for the bottom 128 values.
You need to find out what encoding your files actually use, and specific that when reading the data with StreamReader (or whatever else you're using). For example, you may want encoding Windows-1252:
Encoding encoding = Encoding.GetEncoding(1252);
.NET strings are always sequences of UTF-16 code points. You can't change that, and you shouldn't try. (That's true in Java as well, and you really shouldn't use the platform default encoding when calling getBytes() etc unless that's what you really, really mean.)
An Encoding can be specified in at least one overload of functions for reading text - for example, ReadAllText(string, Encoding).
So if you no a file's encoded using Windows-1252, then you can specify it like so:
string contents = File.ReadAllText(someFilePath, Encoding.GetEncoding(1252));
Of course, doing this requires knowing ahead of time which code page is being used.
I'm not entirely sure if the question even makes sense. I'm converting a byte array taken from an ID3 tag and converting it to a string. Most text frames in an ID3 tag use ISO 8859-1 encoding but it depends on the frame. In any case, if you look up what 0x00 is in the ISO 8859-1 codes it is invalid.
To further complicate, either due programmer error or just poor formatting, some of the strings end in 0x00 and some do not.
When converting a series of bytes into a string using ISO 8859-1 encoding do you have manually check the end of the string to see if it is a null? Or will the encoding object through whatever method it uses to convert in the first place deal with the null properly? Furthermore, is there some sort of function that could normalize or "fix" the null terminated string?
When you try to display these strings they do not display properly.
I am using C# for this particular project.
Some extra info here about ID3 Tags: ID3 Specs
Or am I completely misunderstanding the whole thing? Is a null terminator simply a way a particular language handles strings and it has nothing to do with encoding?
Edit: I used System.Text.Encoding.GetEncoding("iso-8859-1") followed by a GetString call
If you use Encoding.GetEncoding(28591), it just converts a byte 0 to the Unicode U+0000. Encodings generally assume that they have to convert all the bytes - they don't look for terminators.
This treatment of 0 as Unicode 0 is inline with the Wikipedia description:
In 1992, the IANA registered the character map ISO_8859-1:1987, more commonly known by its preferred MIME name of ISO-8859-1 (note the extra hyphen over ISO 8859-1), a superset of ISO 8859-1, for use on the Internet. This map assigns the C0 and C1 control characters to the unassigned code values thus provides for 256 characters via every possible 8-bit value.
The C0 and C1 control characters page includes:
0: Originally used to allow gaps to be left on paper tape for edits. Later used for padding after a code that might take a terminal some time to process (e.g. a carriage return or line feed on a printing terminal). Now often used as a string terminator, especially in the C programming language.
Sample code:
using System;
using System.Text;
class Program
{
static void Main(string[] args)
{
byte[] data = { 0, 0 };
Encoding latin1 = Encoding.GetEncoding(28591);
string text = latin1.GetString(data);
Console.WriteLine(text.Length); // 2
Console.WriteLine((int) text[0]); // 0
Console.WriteLine((int) text[1]); // 0
}
}
Happily, ASCII, ISO-8859-1 and Unicode all agree on codepoints in the range 0..127. Thus your character '\0' will be encoded identically in ASCII, ISO-8859-1 and UTF-8.
If your program assigns special semantics to the zero byte, you have to take care of that appropriately.
Additional information: Unable to
translate Unicode character \uDFFF at
index 195 to specified code page.
I made an algorithm, who's result are binary values (different lengths). I transformed it into uint, and then into chars and saved into stringbuilder, as you can see below:
uint n = Convert.ToUInt16(tmp_chars, 2);
_koded_text.Append(Convert.ToChar(n));
My problem is, that when i try to save those values into .txt i get the previously mentioned error.
StreamWriter file = new StreamWriter(filename);
file.WriteLine(_koded_text);
file.Close();
What i am saving is this: "忿췾᷿］볯褟ﶞ痢ﳻ��伞ﳴ㿯ﹽ翼蛿㐻ﰻ筹��﷿￦ﾏ랿鳿⏟麞펿"... which are some weird signs.
What i need is to convert those binary values into some kind of string of chars and save it to txt. I saw somewhere that converting to UTF8 should help, but i don't know how to. Would changing files encoding help too?
You cannot transform binary data to a string directly. The Unicode characters in a string are encoded using utf16 in .NET. That encoding uses two bytes per character, providing 65536 distinct values. Unicode however has over one million codepoints. To make that work, the Unicode codepoints above \uffff (above the BMP, Basic Multilingual Plane) are encoded with a surrogate pair. The first one has a value between 0xd800 and 0xdbff, the second between 0xdc00 and 0xdfff. That provides 2 ^ (10 + 10) = 1 million additional codes.
You can perhaps see where this leads, in your case the code detects a high surrogate value (0xdfff) that isn't paired with a low surrogate. That's illegal. Lots more possible mishaps, several codepoints are unassigned, several are diacritics that get mangled when the string is normalized.
You just can't make this work. Base64 encoding is the standard way to carry binary data across a text stream. It uses 6 bits per character, 3 bytes require 4 characters. The character set is ASCII so the odds of the receiving program decoding the character back to binary incorrectly are minimal. Only a decades old IBM mainframe that uses EBCDIC could get you into trouble. Or just plain avoid encoding to text and keep it binary.
Since you're trying to encode binary data to a text stream this SO question already contains an answer to the question: "How do I encode something as base64?" From there plain ASCII/ANSI text is fine for the output encoding.
Simple yes or no question, and I'm 90% sure that it is no... but I'm not sure.
Can a Base64 string contain tabs?
It depends on what you're asking. If you are asking whether or not tabs can be base-64 encoded, then the answer is "yes" since they can be treated the same as any other ASCII character.
However, if you are asking whether or not base-64 output can contain tabs, then the answer is no. The following link is for an article detailing base-64, including which characters are considered valid:
http://en.wikipedia.org/wiki/Base64
The short answer is no - but Base64 cannot contain carriage returns either.
That is why, if you have multiple lines of Base64, you strip out any carriage returns, line feeds, and anything else that is not in the Base64 alphabet
That includes tabs.
From wikipedia.com:
The current version of PEM (specified
in RFC 1421) uses a 64-character
alphabet consisting of upper- and
lower-case Roman alphabet characters
(A–Z, a–z), the numerals (0–9), and
the "+" and "/" symbols. The "="
symbol is also used as a special
suffix code. The original
specification, RFC 989, additionally
used the "*" symbol to delimit encoded
but unencrypted data within the output
stream.
As you can see, tab characters are not included. However, you can of course encode a tab character into a base64 string.
Sure. Tab is just ASCII character 9, and that has a base64 representation just like any other integer.
Base64 specification (RFC 4648) states in Section 3.3 that any encountered non-alphabet characters should be rejected unless explicitly allowed by another specification:
Implementations MUST reject the
encoded data if it contains
characters outside the base alphabet
when interpreting base-encoded
data, unless the specification
referring to this document explicitly
states otherwise. Such specifications
may instead state, as MIME does,
that characters outside the base
encoding alphabet should simply be
ignored when interpreting data ("be
liberal in what you accept").
Note that this means that any
adjacent carriage return/ line feed
(CRLF) characters constitute
"non-alphabet characters" and are
ignored.
Specs such as PEM (RFC 1421) and MIME (RFC 2045) specify that Base64 strings can be broken up by whitespaces. Per referenced RFC 822, a tab (HTAB) is considered a whitespace character.
So, when Base64 is used in context of either MIME or PEM (and probably other similar specifications), it can contain whitespace, including tabs, which should be handled (stripped out) while decoding the encoded content.
Haha, as you see from the responses, this is actually not such a simple yes no answer.
A resulting Base64 string after conversion cannot contain a tab character, but It seems to me that you are not asking that, seems to me that you are asking can you represent a string (before conversion) containing a tab in Base64, and the answer to that is yes.
I would add though that really what you should do is make sure that you take care to preserve the encoding of your string, i.e. convert it to an array of bytes with your correct encoding (Unicode, UTF-8 whatever) then convert that array of bytes to base64.
EDIT: A simple test.
private void button2_Click(object sender, EventArgs e)
{
StringBuilder sb = new StringBuilder();
string test = "The rain in spain falls \t mainly on the plain";
sb.AppendLine(test);
UTF8Encoding enc = new UTF8Encoding();
byte[] b = enc.GetBytes(test);
string cvtd = Convert.ToBase64String(b);
sb.AppendLine(cvtd);
byte[] c = Convert.FromBase64String(cvtd);
string backAgain = enc.GetString(c);
sb.AppendLine(backAgain);
MessageBox.Show(sb.ToString());
}
It seems that there is lots of confusion here; and surprisingly most answers are of "No" variety. I don't think that is a good canonical answer.
The reason for confusion is probably the fact that Base64 is not strictly specified; multiple practical implementations and interpretations exist.
You can check out link text for more discussion on this.
In general, however, conforming base64 codecs SHOULD understand linefeeds, as they are mandated by some base64 definitions (76 character segments, then linefeed etc).
Because of this, most decoders also allow for indentation whitespace, and quite commonly any whitespace between 4-character "triplets" (so named since they encode 3 bytes).
So there's a good chance that in practice you can use tabs and other white space.
But I would not add tabs myself if generating base64 content sent to a service -- be conservative at what you send, (more) liberal at what you receive.
Convert.FromBase64String() in the .NET framework does not seem to mind them. I believe all whitespace in the string is ignored.
string xxx = "ABCD\tDEFG"; //simulated Base64 encoded string w/added tab
Console.WriteLine(xxx);
byte[] xx = Convert.FromBase64String(xxx); // convert string back to binary
Console.WriteLine(BitConverter.ToString(xx));
output:
ABCD DEFG
00-10-83-0C-41-46
The relevant clause of RFC-2045 (6:8)
The encoded output stream must be
represented in lines of no more
than 76 characters each. All line
breaks or other characters not
found in Table 1 must be ignored by
decoding software. In base64 data,
characters other than those in Table
1, line breaks, and other white
space probably indicate a transmission
error, about which a warning
message or even a message rejection
might be appropriate under some
circumstances.
YES!
Base64 is used to encode ANY 8bit value (Decimal 0 to 255) into a string using a set of safe characters. TAB is decimal 9.
Base 64 uses one of the following character sets:
Data: ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/
URLs: ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_
Binary Attachments (eg: email) in text are also encoded using this system.