I have a phonebook app where I generate the title for section headers by comparing the first letters of entries.
The indexes are predefined so I expect letters to be assigned from A-Z and for numbers #.
The problem is there are many letter with accents including ü, İ, ç etc in many languages. In my approach, since these chars do not fall under the range A-Z, they are assigned to # which is not desired.
The native iOS Phonebook app assigns for example ü to U and so on. Is there a simple way to make this casting without defining a set of chars?
Thanks.
Check out Unicode Normalization. You probably want some combination of NFD and extraction of the adequate data. If you look at this file from Unicode, you will see something like
00E9;LATIN SMALL LETTER E ACUTE;Ll;0;L;0065 0301;;;;N;;;00C9;;00C9
Where 00E9, ie 'é', is decomposed as 0065 0301. You pick up 0065 (a), and discard 0301 (´). This file should get you started nicely. There may be equivalent functions in Objective-C/iOS, but I wouldn't know where to start...
Related
Turkish has dotted and dotless I as two separate characters, each with their own uppercase and lowercase forms.
Uppercase Lowercase
I U+0049 ı U+0131
İ U+0130 i U+0069
Whereas in other languages using the Latin alphabet, we have
Uppercase Lowercase
I U+0049 i U+0069
Now, The Unicode Consortium could have implemented this as six different characters, each with its own casing rules, but instead decided to use only four, with different casing rules in different locales. This seems rather odd to me. What was the rationale behind that decision?
A possible implementation with six different characters:
Uppercase Lowercase
I U+0049 i U+0069
I NEW ı U+0131
İ U+0130 i NEW
Codepoints currently used:
U+0049 ‹I› \N{LATIN CAPITAL LETTER I}
U+0130 ‹İ› \N{LATIN CAPITAL LETTER I WITH DOT ABOVE}
U+0131 ‹ı› \N{LATIN SMALL LETTER DOTLESS I}
U+0069 ‹i› \N{LATIN SMALL LETTER I}
There is one theoretical and one practical reason.
The theoretical one is that the i of most Latin-script alphabets and the i of the Turkish and Azerbaijani alphabets are the same, and again the I of most Latin-script alphabets and the I of the Turkish and Azerbaijani are the same. The alphabets differ in the relationship between those too. One could easily enough argue that they are in fact different (as your proposed encoding treats them) but that's how the Language Commission considered them in defining the alphabet and orthography in the 1920s in Turkey, and Azerbaijani use in the 1990s copied that.
(In contrast, there are Latin-based scripts for which i should be considered semantically the same as i though never drawn with a dot [just use a different font for differently shaped glyphs], particularly those that date before Carolingian or which derive from one that is, such as how Gaelic script was derived from Insular script. Indeed, it's particularly important never to write Irish in Gaelic script with a dot on the i that could be compared with the sí buailte diacritic of the orthography that was used with it. Sadly many fonts attempting this script make not only add a dot, but make the worse orthographical error of making it a stroke and hence confusable with the fada diacritic, which as it could appear on an i while the sí buailte could not, and so makes the spelling of words appear wrong. There are probably more "Irish" fonts with this error than without).
The practical reason is that existing Turkish character encodings such as ISO/IEC 8859-9, EBCDIC 1026 and IBM 00857 which had common subsets with either ASCII or EBCDIC already treated i and I as the same as those in ASCII or EBCDIC (that is to say, those in most Latin script alphabets) and ı and İ as separate characters which are their case-changed equivalents; exactly as Unicode does now. Compatibility with such scripts requires continuing that practice.
Another practical reason for that implementation is that doing otherwise would create a great confusion and difficulty for Turkish keyboard layout users.
Imagine it was implemented the way you suggested, and pressing the ıI key and the iİ key on Turkish keyboards produced Turkish-specific Unicode characters. Then, even though Turkish keyboard layout otherwise includes all ASCII/Basic Latin characters (e.g. q, w, x are on the keyboard even though they are not in the Turkish alphabet), one character would have become impossible to type. So, for example Turkish users wouldn't be able to visit wikipedia.org, because what they actually typed would be w�k�ped�a.org. Maybe web browsers could implement a workaround specifically for Turkish users, but think of the other use cases and heaps non-localized applications that would become difficult to use. Perhaps Turkish keyboard layout could add an additional key to become ASCII-complete again, so that there are three keys, i.e. ıI, iİ, iI. But it would be a pointless waste of a key in an already crowded layout and would be even more confusing, so Turkish users would need to think which one is appropriate in every context: "I am typing a user name, which tend to expect ASCII characters, so use the iI key here", "When creating my password with the i character, did I use the iI key or the iİ key?"
Due to a myriad of such problems, even if Unicode included Turkish-specific i and I characters, most likely the keyboard layouts would ignore it and continue to use regular ASCII/Basic Latin characters, so the new characters would be completely unused and moot. Except they would still probably occasionally come up in places and create confusion, so it's a good thing that they didn't go that route.
What is the subset of Unicode characters that are normally used in writing — such as those that would be typically found in a newspaper article?
For example, in English, the characters in the range [a-zA-Z0-9], plus some punctuation characters, would be sufficient for most writing.
But I want to support languages that use characters that fall outside the ASCII range, while excluding the non-printing or decorative characters.
The objective is to restrict the user input to the application to codepoints that are legitimately used in written language. Because the user input will be saved and displayed, I do not want to allow pranksters to input text consisting entirely of things like diacritics, Unicode combining characters, Unicode flow control characters, etc.
Regrettably, I am not fluent in every single language found in Unicode. Has anyone compiled a list of all of the subset of Unicode characters that are normally used in writing?
The official list of Unicode code points is UnicodeData.txt. This is a plain text file with one line per code point; it's easily machine-readable. For example:
0022;QUOTATION MARK;Po;0;ON;;;;;N;;;;;
The third semicolon-delimited field is the abbreviated name of the "General Category". This is explained further in chapter 4 of the Unicode Standard, specifically in section 4.5; see the table on page 131 (page 12 of the PDF file). For example, "Lu" is uppercase letters, "Ll" is lowercase letters, Pc, Pd, Ps, et al are various kinds of punctuation. (The first letter of the two-letter abbreviation represents a higher-level category such as letter, digit, punctuation, etc.)
Note that some ranges of code points are not listed explicitly. For example, the range of CJK (Chinese, Japanese, Korean) ideographs is represented as:
4E00;<CJK Ideograph, First>;Lo;0;L;;;;;N;;;;;
9FCC;<CJK Ideograph, Last>;Lo;0;L;;;;;N;;;;;
I think there are other files on unicode.org that fill in these gaps.
I'm still not 100% clear on just what subset you're trying to define, but you can probably define it as a particular set of General Category values.
I do not want to allow pranksters to input text consisting entirely of things like diacritics, Unicode combining characters
Diacritics/combining characters will be used in normal written language. So if you want to stop 'pranksters' you're going to need something more sophisticated than just a list of permitted characters. You'll have to do some sort of linguistic analysis for every language you want to permit.
I'd recommend not bothering with this, because it's going to be hard and you won't succeed anyway. Just let people write what they want.
Try WGL4 (652 characters), MES-1 (335 characters) or MES-2 (1062 characters). Find these at Wikipedia.
You may wish to exclude characters IJijĸĿŀʼn˚―⅛⅜⅝⅞♪ from MES-1 if you want to use this set.
Edit: I realize this is a bad answer. Especially the removing characters from MES-1 part was total garbage. I shouldn't have posted this. I'm ashamed of whoever upvoted this.
If anything, use Subset1 (678 characters), Subset2 (1193 characters) and Subset3 (2823 characters). https://unicodesubsets.miraheze.org/wiki/User:PiotrGrochowski
Does there exist a standard Perl module or function that, given a Unicode Combining Character Sequence (or, more generally, an arbitrary Unicode text string), will generate a list of all canonically equivalent strings?
For example, if given the character U+1EAD, I'd like to get back a list of all these canonically equivalent sequences:
0061 0302 0323
0061 0323 0302
00E2 0323
1EA1 0302
1EAD
(I don't particularly care whether the interface is in terms of arrays of USVs or utf strings.)
Is this an XY problem? If you want to compare/match 2 unicode strings and you're worried that different ways of encoding the accented characters would create false negatives, then the best way to do this would be to normalize the 2 strings using one of the normalization functions from Unicode::Normalize, before doing the comparison or match.
Otherwise it gets a little messy.
You could get the complete character name using charnames::viacode(0x1EAD); (for U+1EAD it would be LATIN SMALL LETTER A WITH CIRCUMFLEX AND DOT BELOW), and get the various composing characters by splitting the name on WITH|AND. Then you could generate all combinations (checking that they exist!) of the base character + modifiers and the other modifiers. At this point you will run into the problem of matching the combining characters names in the full name (eg CIRCUMFLEX) with the combining character real name (COMBINING CIRCUMFLEX ACCENT). There are probably rules for this, but I don't know them.
This would be my naive attempt, there may be better ways of doing this, but since so far no one has volunteered the information...
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.