I've made a program in MVSC++ which outputs memory contents (in ASCII). The ASCII I see in windows console seem to match what I see in various ASCII tables (smiley, diamond, club, right arrow etc). This program needs to compile under Linux (which is does), but the ASCII output looks completely different. A few symbols are the same but the rest are so different. Is there any way to change how terminal displays ASCII code?
EDIT: The program executes correctly, it's just the ASCII that is being displayed differently.
ASCII defines character codes from 0x00 through 0x7f. Everything else (0x80-0xff) is not part of the ASCII standard and depends on what the operating system defines as the characters to display. However, the characters you mention (smiley, diamond, club, etc) are the representations of the ASCII "control characters" that don't normally have a visual representation. Windows lets you print such characters and see the glyphs it has defined for them, but your Linux is probably interpreting the control characters as formatting control codes (which they are) instead of printing corresponding glyphs.
What you are seeing is the "extended" character set that IBM initially included when PCs were first unleashed upon the world. Yes, we are going back to the age of mighty dinosaurs, so bear with me. These characters live above $7F and the interpretation of their symbols on the screen can even be influenced by the font chosen. Most linux distros are now using UTF-8 (or something close) and as such, the fonts installed may have completely different symbols, or even missing glyphs. In cases where you are comparing "ASCII" representations (which is a misnomer, as it's not really true ASCII) of the same data, it may or may not exactly match, as you must have the same "glyph" renderings in both display fonts to correctly see similar representations. Try getting both your Windows and Linux installs to use the same font if possible, and then see if there is a change.
If your browser supports Unicode (and you have the correct fonts installed), you will see them bellow.
You can copy and paste into an editor with unicode support(Notepad). Save as UTF-16BE
Then if you open in a HexEditor you will see all the unicode codes for each char visible glyph.
In example the first ascii char Null has Unicode visible glyph 0x2639
in c\c++\java you can use it like \u2639.
Its not a null char but the visual representation.
http://en.wikipedia.org/wiki/Code_page_437
☹☺☻♥♦♣♠•◘○◙♂♀♪♫☼►◄↕‼¶§▬↨↑↓→←∟↔▲▼ !"#$%&'()*+,-./0123456789:;<=>?#ABCDEFGHIJKLMNOPQRSTUVWXYZ[]^_`abcdefghijklmnopqrstuvwxyz{|}~⌂ÇüéâäàåçêëèïîìÄÅÉæÆôöòûùÿÖÜ¢£¥₧ƒáíóúñѪº¿⌐¬½¼¡«»░▒▓│┤╡╢╖╕╣║╗╝╜╛┐└┴┬├─┼╞╟╚╔╩╦╠═╬╧╨╤╥╙╘╒╓╫╪┘┌█▄▌▐▀αßΓπΣσµτΦΘΩδ∞φε∩≡±≥≤⌠⌡÷≈°∙·√ⁿ²■⓿
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In the following code, the ü is not the single Unicode character U+00FC but is a single grapheme cluster composed of two Unicode characters, the plain ASCII u U+0075 followed by the combining diaeresis U+0308.
fmt.Println("Jürgen Džemal")
fmt.Println("Ju\u0308rgen \u01c5emel")
If I run it in the go playground, it works as expected.
If I run it in a MS Windows 10 "Command Prompt" window, it doesn't visually combine the combining character with the prior character.
However when I cut and paste the text into here it appears correctly:
C:\> ver
Microsoft Windows [Version 10.0.17134.228]
C:\> test
Jürgen Džemal
Jürgen Džemel
On screen, in the "Command Prompt" window it looked more like:
Ju¨rgen Džemel
Changing the code page (chcp) from 850 to 65001 made no difference. Changing fonts (Consolas, Courier etc) made no difference.
In the past I have experienced problems that were fundamentally because Microsoft require Windows programs to use a different API to output characters to STDOUT depending on whether STDOUT is attached to a console or to a file. I don't know if this is a different manifestation of the same issue.
Is there something I can do to make this Unicode grapheme-cluster appear correctly?
As eryksun and Peter commented,
The Windows console (conhost.exe) doesn't support combining codes. You'll have to first normalize to an equivalent string that uses precomposed characters.
you can use golang.org/x/text/unicode/norm to do the normalization (e.g. norm.NFC.String("Jürgen Džemal"))
I tried this
s := "Ju\u0308rgen \u01c5emel"
fmt.Println(s) // dieresis not combined with u by conhost.exe
s = norm.NFC.String(s)
fmt.Println(s) // shows correctly
And the output looked like this
or, for the visually impaired with fabulously sophisticated screen readers - a bit like this:
Ju¨rgen Džemel
Jürgen Džemel
Note that Unicode has four different normalised forms but NFC is the most used on the Internet in web-pages and is also appropriate for this situation.
There are other methods in this package that may be more efficient or more useful
I read there are visual-characters in use which can only be represented in Unicode using combining characters. In other words for which there is no precomposed character. A more thorough approach would be needed to do something appropriate with those. Essentially the complications of Unicode (or perhaps more accurately of human languages and their typography) are almost without end. It sometimes seems that way to me.
References
https://blog.golang.org/normalization
https://godoc.org/golang.org/x/text/unicode/norm
https://learn.microsoft.com/en-us/windows/desktop/intl/using-unicode-normalization-to-represent-strings
For example, several characters used in writing Lithuanian have double diacritics, as they have only decomposed forms. An example is lowercase U with macron and tilde ("ū̃", U+016b U+0303, where the first code point is a lowercase U with macron and the second is a combining acute accent).
I have been writing a new command line application in C++. One platform we support is, of course, Windows.
The Windows console, by default, uses the OEM code pages depending on the locale (for example, on my machine it is CP437 / DOS.Western). I think, if it was a Windows Cyrillic version, it would have been CP866, and so on. These OEM code pages contain only 256 characters)
I think what this means is the Windows console translates the input key strokes into characters based on the default code page. (And, depending on the currently selected fonts, if there is a corresponding glyph, it is displayed).
In such a case, whether does it makes sense to use wmain/wchar_t and wide char types in my application?
Is there any advantage of using wide types? Or is there any grave problem if just char * is used?
When wide char types are used, what is the encoding of the command line arguments and environment strings - (wchar_t * argv[] and wchar_t * envp[]), i mean. Are they converted to UTF-16 by Windows CRT, or are they untouched?
Thanks for your contributions.
You seem to be assuming that Windows internally works in the specified codepage. That's not true. Windows internally works in Unicode (UTF-16). For legacy software that uses char instead of wchar_t, input and output are translated into the specified codepage.
I think what this means is the Windows console translates the input key strokes into characters based on the default code page
This is not correct. The mapping of key strokes to (Unicode) characters is defined by the keyboard layout. This is totally independent of the code page. E.g you could use a Chinese keyboard layout on a system using a Cyrillic code page.
Not only makes it totally sense to usewchar_t, it is the recommended way.
Yes, there is an advantage: your program can process all characters supported by Windows. If you use char, you can't handle any characters that are not in the current code page.
They are not converted - they stay what they are, namely UTF-16 characters.
Unfortunately, the command prompt itself is an 'ANSI' application, so it suffers from all of the limitations of 'ANSI', and this affects your application if you use it from the command prompt. However, a console application can be used in other ways, without a command prompt window, and then it can support Unicode fully.
I know that this is a little vague, so for context, think of it as "a character you could tweet," or something like that. My question is how many valid unicode characters are there that a browser or a service that supports utf8 could resolve, in such a way that a utf8 browser could copy and paste it around without any issues.
I guess what I don't want is the full character space, because I know a lot of it is reserved for command characters or reserved characters that wouldn't be shown (unless I'm super wrong!).
UTF-8 isn't the important factor, since all of the standard Unicode encodings (UTF-8, UTF-16, UTF-32) encode the same character space, just in different ways.
From your explanation I see you don't just want the 1,112,064 valid Unicode code points?
Unicode 6.0 and ISO/IEC 10646:2010 define 109,449 characters, but a handful of those are what you're calling "control characters". Which ones do or don't fall into that category depends on how you're counting. Copying and pasting may result in some characters being treated as identical to one another, or ignore altogether, depending on the OS and the programs doing the copying and pasting.
However because Unicode is forward compatible, some systems will correctly preserve characters which haven't yet been assigned. After all, just because you're running Windows XP and you copy and paste a document with characters that weren't standardised until 2009 doesn't mean you expect them to vanish. There could be a million or so extra possible characters by this way of thinking, although their visual appearance may be indistinguishable in some places.
Excuse me if the question is stupid, it's kind of confused me, suppose I have a application(no matter C, C++,.NET or Java) on my Windows XP, and this application will get data from a remote machine, the data contain Chinese characters, now if Chinese characters become junk, is it correct to say that Windows has nothing to do with this issue? because Windows uses UTF-16, and can handle Chinese characters properly.
On the other hand, suppose Windows uses ASCII as its internal encoding, does this mean that any applications on it can never display Chinese characters correctly?
Thanks in advance.
The Windows NT kernel uses UNICODE_STRING for many (or is it most?) named objects (e.g. files). The encoding is UTF-16.
Many of user-mode callable APIs expose pairs of almost identical functions, where one in the pair accepts Unicode strings and, the other, ANSI strings. The ANSI string versions end up converting names from ANSI to Unicode.
For example, when you call C's fopen() function, which accepts 8-bit non-Unicode file names, it ends up invoking CreateFileA() (ANSI), and that eventually calls NtCreateFile(), which accepts Unicode file names. One of NtCreateFile()'s parameters, the OBJECT_ATTRIBUTES structure, contains a pointer to a UNICODE_STRING structure.
If you, on the other hand, call MSVC++'s _wfopen() function, it will reach NtCreateFile() through CreateFileW() (Unicode) without the conversion.
To store any text in memory and display it on screen, the OS needs to handle that text in some encoding behind the scenes. What encoding that is specifically shouldn't matter to you. It could handle it as HTML encoded ASCII for all you know, as long as the APIs accept certain text and it outputs the right thing.
"Windows uses UTF-16 internally" means Windows happens to store and handle text internally as UTF-16. It also supports Chinese text. These two things aren't necessarily connected. Yes, using UTF-16 internally makes it easier to support Chinese, which is probably why the Windows engineers chose to go with UTF-16.
This is quite a low-level (low in the sense of "closer to the metal") question.
I was wondering if any of you could point me to documentation, explanations, etc. of how, upon receiving a Unicode character (or any character code, but I'm particularly interested in the Unicode Standard) the console in Windows, good ol' cmd.exe (using, say, codepage 65001) and xterm in Linux started with, say, LC_CTYPE=en_US.UTF-8 look up the corresponding glyph (and where).
I know it may be harder to know in Windows, but I can't really find much information.
Thank you.
As far as I can tell, cmd.exe is bound to whatever 256-character code page you defined as the "codepage for non-Unicode programs" or whatever it was called.
To elaborate, if I set the above setting to Japanese, cmd.exe suddenly replaces backslashes with yen signs (as does every other non-Unicode app on the system) and correctly interprets ShiftJIS codes, for example. Setting it to Dutch gives me an accented I (I forgot which), while another codepage would give a half-filled vertical solid instead on the same character.
Not Unicode. Unicode would let me do all three at the same time.
The console uses a TextWriter with an encoding created from the codepage. That means that the characters written are encoded into bytes using the specific Encoding object for the codepage.
the console doesn't support Unicode. :)