We are looking for a "BREAK NO-SPACE" character reverse to NO-BREAK SPACE. It should not print anything, just indicate the components down the line, the word can be split and linebroken at these positions.
Is there anything similar to this in Unicode or any other encoding scheme? It would make life easier since we could then rely on built-in methods for line split in our framework instead of introducing custom logic and some "Magic Character".
Soft hyphen U+00AD is invisible but indicates where a word should be broken.
So I found the Zero Width Space character 200B. The documentation describes exactly what I was looking for.
Please help find superscript j Unicode character code, if it is present. If not, do you know why?
I look up on Wikipedia. There is ⁱ, but no j.
Well, there's U+02B2 MODIFIER LETTER SMALL J. That said, as the name implies, it's intended for cases where a superscript 'j' serves as a sort of diacritic (e.g. in IPA, where it denotes that the previous consonant is palatalized). Using it as a pure superscript would be cheating; see "Why doesn't Unicode have a full set of superscripts and subscripts?" in the Unicode FAQ.
What is the likelihood that I'll run into COMBINING LATIN SMALL LETTER C (U+0368) in "real life" (besides clever Scottish folk)?
I'm asking since it's in both the Unicode Block Combining Diacritical Marks and the Category Mark, Nonspacing [Mn].
As a result, it seems to gets treated the same as characters such as COMBINING GRAVE ACCENT (U+0300) by Utilities such as the ICU Transliterator (using either the suggested "NFD; [:Nonspacing Mark:] Remove; NFC" or a straight "Latin-ASCII" transliteration).
The likelihood is very close to zero, but not exactly zero. You cannot prevent anyone from using a Unicode character as he likes. There is no specific information about U+0368 in the Unicode Standard, but it has definitely been defined as a combining character that will cause a symbol (c) to be displayed above the preceding character. I would expect to find it mostly in digitized forms of medieval manuscripts, or something like that.
Using it after a space character, as in the “clever” page mentioned, is not the intended use, but not invalid either. Unicode lets you use any combining mark after any character, whether it makes sense or not.
It has no canonical or compatibility decomposition, so there is no clear-cut way to deal with in a context where you cannot, or do not want to, retain the character.
The likelihood is utterly indeterminate except to say that if you expect it not to occur, then it will occur.
Can anybody please tell me what is the range of Unicode printable characters? [e.g. Ascii printable character range is \u0020 - \u007f]
See, http://en.wikipedia.org/wiki/Unicode_control_characters
You might want to look especially at C0 and C1 control character http://en.wikipedia.org/wiki/C0_and_C1_control_codes
The wiki says, the C0 control character is in the range U+0000—U+001F and U+007F (which is the same range as ASCII) and C1 control character is in the range U+0080—U+009F
other than C-control character, Unicode also has hundreds of formatting control characters, e.g. zero-width non-joiner, which makes character spacing closer, or bidirectional text control. This formatting control characters are rather scattered.
More importantly, what are you doing that requires you to know Unicode's non-printable characters? More likely than not, whatever you're trying to do is the wrong approach to solve your problem.
This is an old question, but it is still valid and I think there is more to usefully, but briefly, say on the subject than is covered by existing answers.
Unicode
Unicode defines properties for characters.
One of these properties is "General Category" which has Major classes and subclasses. The Major classes are Letter, Mark, Punctuation, Symbol, Separator, and Other.
By knowing the properties of your characters, you can decide whether you consider them printable in your particular context.
You must always remember that terms like "character" and "printable" are often difficult and have interesting edge-cases.
Programming Language support
Some programming languages assist with this problem.
For example, the Go language has a "unicode" package which provides many useful Unicode-related functions including these two:
func IsGraphic(r rune) bool
IsGraphic reports whether the rune is defined as a Graphic by Unicode. Such
characters include letters, marks, numbers, punctuation, symbols, and spaces,
from categories L, M, N, P, S, Zs.
func IsPrint(r rune) bool
IsPrint reports whether the rune is defined as printable by Go. Such
characters include letters, marks, numbers, punctuation, symbols, and
the ASCII space character, from categories L, M, N, P, S and the ASCII
space character. This categorization is the same as IsGraphic except
that the only spacing character is ASCII space, U+0020.
Notice that it says "defined as printable by Go" not by "defined as printable by Unicode". It is almost as if there are some depths the wizards at Unicode dare not plumb.
Printable
The more you learn about Unicode, the more you realise how unexpectedly diverse and unfathomably weird human writing systems are.
In particular whether a particular "character" is printable is not always obvious.
Is a zero-width space printable? When is a hyphenation point printable? Are there characters whose printability depends on their position in a word or on what characters are adjacent to them? Is a combining-character always printable?
Footnotes
ASCII printable character range is \u0020 - \u007f
No it isn't. \u007f is DEL which is not normally considered a printable character. It is, for example, associated with the keyboard key labelled "DEL" whose earliest purpose was to command the deletion of a character from some medium (display, file etc).
In fact many 8-bit character sets have many non-consecutive ranges which are non-printable. See for example C0 and C1 controls.
First, you should remove the word 'UTF8' in your question, it's not pertinent (UTF8 is just one of the encodings of Unicode, it's something orthogonal to your question).
Second: the meaning of "printable/non printable" is less clear in Unicode. Perhaps you mean a "graphical character" ; and one can even dispute if a space is printable/graphical. The non-graphical characters would consist, basically, of control characters: the range 0x00-0x0f plus some others that are scattered.
Anyway, the vast majority of Unicode characters (more than 200.000) are "graphical". But this certainly does not imply that they are printable in your environment.
It seems to me a bad idea, if you intend to generate a "random printable" unicode string, to try to include all "printable" characters.
What you should do is pick a font, and then generate a list of which Unicode characters have glyphs defined for your font. You can use a font library like freetype to test glyphs (test for FT_Get_Char_Index(...) != 0).
Taking the opposite approach to #HoldOffHunger, it might be easier to list the ranges of non-printable characters, and use not to test if a character is printable.
In the style of Regex (so if you wanted printable characters, place a ^):
[\u0000-\u0008\u000B-\u001F\u007F-\u009F\u2000-\u200F\u2028-\u202F\u205F-\u206F\u3000\uFEFF]
Which accounts for things like separator spaces and joiners
Note that unlike their answer which is a whitelist that ignores all non-latin languages, this blacklist wont permit non-printable characters just because they're in blocks with printable characters (their answer wholly includes Non-Latin, Language Supplement blocks as 'printable', even though it contains things like 'zero-width non-joiner'..).
Be aware though, that if using this or any other solution, for sanitation for example, you may want to do something more nuanced than a blanket replace.
Arguably in that case, non-breaking spaces should change to space, not be removed, and invisible separator should be replaced with comma conditionally.
Then there's invalid character ranges, either [yet] unused or reserved for encoding purposes, and language-specific variation selectors..
NB when using regular expressions, that you enable unicode awareness if it isn't that way by default (for javascript it's via /.../u).
You can tell if you have it correct by attempting to create the regular expression with some multi-byte character ranges.
For example, the above, plus the invalid character range \u{E0100}-\u{E01EF} in javascript:
/[\u0000-\u0008\u000B-\u001F\u007F-\u009F\u2000-\u200F\u2028-\u202F\u205F-\u206F\u3000\uFEFF\u{E0100}-\u{E01EF}]/u
Without u \u{E0100}-\u{E01EF} equates to \uDB40(\uDD00-\uDB40)\uDDEF, not (\uDB40\uDD00)-(\uDB40\uDDEF), and if replacing you should always enable u even when not including multbyte unicode in the regex itself as you might break surrogate pairs that exist in the text.
What characters are valid?
At present, Unicode is defined as starting from U+0000 and ending at U+10FFFF. The first block, Basic Latin, spans U+0000 to U+007F and the last block, Supplementary Private Use Area-B, spans U+100000 to 10FFFF. If you want to see all of these blocks, see here: Wikipedia.org: Unicode Block; List of Blocks.
Let's break down what's valid/invalid in the Latin Block1.
The Latin Block: TLDR
If you're interested in filtering out either invisible characters, you'll want to filter out:
U+0000 to U+0008: Control
U+000E to U+001F: Device (i.e., Control)
U+007F: Delete (Control)
U+008D to U+009F: Device (i.e., Control)
The Latin Block: Full Ranges
Here's the Latin block, broken up into smaller sections...
U+0000 to U+0008: Control
U+0009 to U+000C: Space
U+000E to U+001F: Device (i.e., Control)
U+0020: Space
U+0021 to U+002F: Symbols
U+0030 to U+0039: Numbers
U+003A to U+0040: Symbols
U+0041 to U+005A: Uppercase Letters
U+005B to U+0060: Symbols
U+0061 to U+007A: Lowercase Letters
U+007B to U+007E: Symbols
U+007F: Delete (Control)
U+0080 to U+008C: Latin1-Supplement symbols.
U+008D to U+009F: Device (i.e., Control)
U+00A0: Non-breaking space. (i.e., )
U+00A1 to U+00BF: Symbols.
U+00C0 to U+00FF: Accented characters.
The Other Blocks
Unicode is famous for supporting non-Latin character sets, so what are these other blocks? This is just a broad overview, see the wikipedia.org page for the full, complete list.
Latin1 & Latin1-Related Blocks
U+0000 to U+007F : Basic Latin
U+0080 to U+00FF : Latin-1 Supplement
U+0100 to U+017F : Latin Extended-A
U+0180 to U+024F : Latin Extended-B
Combinable blocks
U+0250 to U+036F: 3 Blocks.
Non-Latin, Language blocks
U+0370 to U+1C7F: 55 Blocks.
Non-Latin, Language Supplement blocks
U+1C80 to U+209F: 11 Blocks.
Symbol blocks
U+20A0 to U+2BFF: 22 Blocks.
Ancient Language blocks
U+2C00 to U+2C5F: 1 Block (Glagolitic).
Language Extensions blocks
U+2C60 to U+FFEF: 66 Blocks.
Special blocks
U+FFF0 to U+FFFF: 1 Block (Specials).
One approach is to render each character to a texture and manually check if it is visible. This solution excludes spaces.
I've written such a program and used it to determine there are roughly 467241 printable characters within the first 471859 code points. I've selected this number because it covers all of the first 4 Planes of Unicode, which seem to contain all printable characters. See https://en.wikipedia.org/wiki/Plane_(Unicode)
I would much like to refine my program to produce the list of ranges, but for now here's what I am working with for anyone who needs immediate answers:
https://editor.p5js.org/SamyBencherif/sketches/_OE8Y3kS9
I am posting this tool because I think this question attracts a lot of people who are looking for slightly different applications of knowing printable ranges. Hopefully this is useful, even though it does not fully answer the question.
The printable Unicode character range, excluding the hex, is 32 to 126 in the int datatype.
Unicode, stict term, has no range. Numbers can go infinite.
What you gave is not UTF8 which has 1 byte for ASCII characters.
As for the range, I believe there is no range of printable characters. It always evolves. Check the page I gave above.
Does someone know a easy way to find characters in Unicode that are similar to ASCII characters. An example is the "CYRILLIC SMALL LETTER DZE (ѕ)". I'd like to do a search and replace for similar characters. By similar I mean human readable. You can't see a difference by looking at it.
As noted by other commenters, Unicode normalisation ("compatibilty characters") isn't going to help you here as you aren't looking for official equivalences but for similarities in glyphs (letter shapes). (The linked Unicode Technical Report is still worth reading, though, as it is extremely well written.)
If I were you, to spare you the tedious work of assembling a list of characters yourself, I'd search for resources on homograph attacks: This is a method of maliciously misleading web users by displaying URLs containing domain names in which some letters have been replaced with visually similar letters. Another Unicode Technical Report, on security, contains a section on the problem. There is also -- and that may be what you most need -- a "confusables" table. Here's another article with mainly punctuation marks, some of which ASCII, that have visually similar counterparts in the non-ASCII code tables.
What I do hope is that you aren't asking the question to construct such an attack.
See the Unicode Database: http://www.unicode.org/Public/UNIDATA/UnicodeData.txt.
Each line describes a unicode caharacter, for example:
1E9A;LATIN SMALL LETTER A WITH RIGHT HALF RING;Ll;0;L;<compat> 0061 02BE;;;;N;;;;;
If there's any similar (compatible) characters for that symbol, it will appear in the <compat> field of the entry. In this example, 0061 (ASCII a) is compatible to the LATIN SMALL LETTER A WITH RIGHT HALF RING Unicode character.
As for your character, the entry is
0455;CYRILLIC SMALL LETTER DZE;Ll;0;L;;;;;N;;;0405;;0405
which, as you can see, does not specify a compatibility character.