I'm trying to convert a string to UTF8, on both obj-c and php.
I get different results:
"\xd7\x91\xd7\x93\xd7\x99\xd7\xa7\xd7\x94" //Obj-C
"\u05d1\u05d3\u05d9\u05e7\u05d4" //PHP
Obj-C code:
const char *cData = [#"בדיקה" cStringUsingEncoding:NSUTF8StringEncoding]
PHP code:
utf8_encode('בדיקה')
This difference breaks my hash algorithm that follows.
How can I make the two strings encoded the same way? Should I change the obj-c\php ?
Go to http://www.utf8-chartable.de/unicode-utf8-table.pl
In the combo box switch to “U+0590 … U+5FF Hebrew”
Scroll down to “U+05D1” which is the rightmost character of your input string.
The third column shows the two UTF-8 bytes: “d7 91”
If you keep looking you will see that the PHP and the Objective-C are actually the same. The “problem” you are seeing is that while PHP uses an Unicode escape (\u), Objective-C uses direct byte hexadecimal escapes (\x). Those are only visual representations of the strings, the bytes in memory are actually the same.
If your hash algorithm deals with bytes correctly, you should not see differences.
What are you using to do the encoding on PHP? It looks like you're generating a UTF-16 string.
Try utf8_encode() and see if that gives better results.
Related
I received a string with an unknown character encoding via import. How can I display such a string in the browser so that it can be reproduced as PHP code?
I would like to illustrate the problem with an example.
$stringUTF8 = "The price is 15 €";
$stringWin1252 = mb_convert_encoding($stringUTF8,'CP1252');
var_dump($stringWin1252); //string(17) "The price is 15 �"
var_export($stringWin1252); // 'The price is 15 �'
The string delivered with var_export does not match the original. All unrecognized characters are replaced by the � symbol. The string is only generated here with mb_convert_encoding for test purposes. Here the character coding is known. In practice, it comes from imports e.G. with file_cet_contents() and the character coding is unknown.
The output with an improved var_export that I expect looks like this:
"The price is 15 \x80"
My approach to the solution is to find all non-UTF8 characters and then show them in hexadecimal. The code for this is too extensive to be shown here.
Another variant is to output all characters in hexadecimal PHP notation.
function strToHex2($str) {
return '\x'.rtrim(chunk_split(strtoupper(bin2hex($str)),2,'\x'),'\x');
}
echo strToHex2($stringWin1252);
Output:
\x54\x68\x65\x20\x70\x72\x69\x63\x65\x20\x69\x73\x20\x31\x35\x20\x80
This variant is well suited for purely binary data, but quite large and difficult to read for general texts.
My question in other words:
How can I change all non-UTF8 characters from a string to the PHP hex representation "\xnn" and leave correct UTF8 characters.
I'm going to start with the question itself:
How can I reproducibly represent a non-UTF8 string in PHP (Browser)
The answer is very simple, just send the correct encoding in an HTML tag or HTTP header.
But that wasn't really your question. I'm actually not 100% sure what the true question is, but I'm going to try to follow what you wrote.
I received a string with an unknown character encoding via import.
That's really where we need to start. If you have an unknown string, then you really just have binary data. If you can't determine what those bytes represents, I wouldn't expect the browser or anyone else to figure it out either. If you can, however, determine what those bytes represent, then once again, send the correct encoding to the client.
How can I display such a string in the browser so that it can be reproduced
as PHP code?
You are round-tripping here which is asking for problems. The only safe and sane answer is Unicode with one of the officially support encodings such as UTF-8, UTF-16, etc.
The string delivered with var_export does not match the original. All unrecognized characters are replaced by the � symbol.
The string you entered as a sample did not end with a byte sequence of x80. Instead, you entered the € character which is 20AC in Unicode and expressed as the three bytes xE2 x82 xAC in UTF-8. The function mb_convert_encoding doesn't have a map of all logical characters in every encoding, and so for this specific case it doesn't know how to map "Euro Sign" to the CP1252 codepage. Whenever a character conversion fails, the Unicode FFFD character is used instead.
The string is only generated here with mb_convert_encoding for test purposes.
Even if this is just for testing purposes, it is still messing with the data, and the previous paragraph is important to understand.
Here the character coding is known. In practice, it comes from imports e.g. with file_get_contents() and the character coding is unknown.
We're back to arbitrary bytes at this point. You can either have PHP guess, or if you have a corpus of known data you could build some heuristics.
The output with an improved var_export that I expect looks like this:
"The price is 15 \x80"
Both var_dump and var_export are intended to show you quite literally what is inside the variable, and changing them would have a giant BC problem. (There actually was an RFC for making a new dumping function but I don't think it did what you want.)
In PHP, strings are just byte arrays so calling these functions dumps those byte arrays to the stream, and your browser or console or whatever takes the current encoding and tries to match those bytes to the current font. If your font doesn't support it, one of the replacement characters is shown. (Or, sometimes a device tries to guess what those bytes represent which is why you see € or similar.) To say that again, your browser/console does this, PHP is not doing that.
My approach to the solution is to find all non-UTF8 characters
That's probably not what you want. First, it assumes that the characters are UTF-8, which you said was not an assumption that you can make. Second, if a file actually has byte sequences that aren't valid UTF-8, you probably have a broken file.
How can I change all non-UTF8 characters from a string to the PHP hex representation "\xnn" and leave correct UTF8 characters.
The real solution is to use Unicode all the way through your application and to enforce an encoding whenever you store/output something. This also means that when viewing this data that you have a font capable of showing those code points.
When you ingest data, you need to get it to this sane point first, and that's not always easy. Once you are Unicode, however, you should (mostly) be safe. (For "mostly", I'm looking at you Emojis!)
But how do you convert? That's the hard part. This answer shows how to manually convert CP1252 to UTF-8. Basically, repeat with each code point that you want to support.
If you don't want to do that, and you really want to have the escape sequences, then I think I'd inspect the string byte by byte, and anything over x7F gets escaped:
$s = "The price is 15 \x80";
$buf = '';
foreach(str_split($s) as $c){
$buf .= $c >= "\x80" ? '\x' . bin2hex($c) : $c;
}
var_dump($buf);
// string(20) "The price is 15 \x80"
I'm using PHP for this web development project. Right now, I'm working on a user page, where the user can add words that he knows. Off course, I'm starting out crude, without adding any special features yet like Do you know this Character suggestion, etc.
I have tackled the challenges of adding UTF-16 collation and charset set to UTF-16 in my MySQL Database, in fact online at http://freemysqlhosting.net to support Chinese characters in my website. Now what I'm struggling with is to support automatic PinYin generation for my Chinese characters.
I have found this after searching all over SO: https://github.com/reorx/pinyindep/blob/master/Uni2Pinyin. Each line begins with a Chinese character, in UTF-16 Code Units.
Take for example, 爱. In UTF-16, it is 7231. I convert this at https://r12a.github.io/apps/conversion/. When I do a lookup in the file, I get the pinyin associated. :D This is the functionality I need, though looking it up in GitHub is in JS, rather than PHP.
In the manual lookup, ai4 is returned, which is the correct intonation. Now, what I'm looking for is either a PHP Built-in Library, or a code snippet to convert this string input, let's say “爱” into a UTF-16 Four Character Code Unit, such as here 7321.
So what's the question:
How should I convert a Chinese character, in form of a string, to UTF-16 code units? (Either through built-in library, or through a suggested PHP Code Snippet)
P.S. I don't really like third-party tools unless they are really popular worldwide, or there's no other option.
You need to use PHP's multibyte string module:
$c = "爱";
list(, $d) = unpack('N', mb_convert_encoding($c, 'UCS-4BE', 'UTF-8'));
echo dechex($d);
// => 7231
Change UTF-8 to UTF-16 if your string is coming from the database in that encoding.
mb_convert_encoding will change the string into four-byte-per-character encoding; then unpack converts the four bytes into an unsigned long; finally, converting to hexadecimal string using dechex.
If you are using PHP 7.2+ you can use mb_ord to simplify the conversion.
echo dechex(mb_ord("爱"));
I want a string to sha1 encoding, then to hex, with a length of 40 characters. This is a Java webservice and the client side is to be done with PHP.
Original code is Java (I don't have the source, only the documentation) and it hashes the following string:
chNFe=43120910585504000174650010000000541123456781&nVersao=100&tpAmb=2&
dhEmi=323031322d30392d32375431363a32303a33342d30333a3030&vNF=1000.00&vICMS=180.00&digVal=37327151612b623074616f514f3966414a7766646c5875715176383d&cIdToken=0000011058550420130001
To the following hex:
3FACB55248244D98C658FC8A826413BCEF10A4AE
The example above is from the webservice documentation and it says string was encoded with sha1, then the result was encoded to hex.
I tried sha1 then dechex and many other ways, but cannot get the same result. Has anyone an idea of what type of encoding PHP have to do to get this hash?
Thank you.
The NFE manual is wrong. The example String has a white space at the end of string..
where appears
5176383d&cIdToken=000001105855042013000 is really
5176383d &cIdToken=000001105855042013000
Convencional functions the cript this using sha1 resolves the problem ;)
in mysql you can do :
sha1(yourExampleString)...
in php could have the something like...
At the moment, I don't understand why it is really important to use mbstring functions in PHP when dealing with UTF-8? My locale under linux is already set to UTF-8, so why doesn't functions like strlen, preg_replace and so on don't work properly by default?
All of the PHP string functions do not handle multibyte strings regardless of your operating system's locale. That is why you need to use the multibyte string functions.
From the Multibyte String Introduction:
When you manipulate (trim, split, splice, etc.) strings encoded in a
multibyte encoding, you need to use special functions since two or
more consecutive bytes may represent a single character in such
encoding schemes. Otherwise, if you apply a non-multibyte-aware string
function to the string, it probably fails to detect the beginning or
ending of the multibyte character and ends up with a corrupted garbage
string that most likely loses its original meaning.
Here is my answer in plain English.
A single Japanese and Chinese and Korean character take more than a single byte. Eg., a typical charactert say x is takes 1 byte in English it will take more than 1 byte in Japanese and Chinese and Korean. Now PHP's standard string functions are meant to treat a single character as 1 byte. So in case you are trying to do compare two Japanese or Chinese or Korean characters they will not work as expected. For example the length of "Hello World!" in Japanese or Chinese or Korean will have more than 12 bytes.
Read http://www.php.net/manual/en/intro.mbstring.php
You do not need to use UTF-8 aware code to process UTF-8. For the most part.
I've even written a Unicode uppercaser/lowercaser, and NFC and NFD transforms, using only byte-aware functions. It's hard to think of anything more complicated than that, that needs such delicate and detailed treatment of UTF-8. And yet it still works with byte-only functions.
It's very rare that you need UTF-8 aware code. Maybe to count the number of characters, or to move an insertion point forward by 1 character. But actually, even then your code won't work ;) because of decomposed characters.
But if all you are doing is replacements, finding stuff, or even parsing syntax, you just need byte-aware functions.
I'll explain why.
It's because no UTF-8 character can be found inside any other UTF-8 character. That's how it is designed.
Try to explain to me how you can get text processing errors, in terms of a multi-byte system where no character can be found inside another character? Just one example case! The simplest you can think of.
PHP strings are just plain byte sequences. They have no meaning by themselves. And they do not use any particular character encoding either.
So if you read a file using file_get_contents() you get a binary-safe representation of the file. May it be the (binary) representation of an image or a human-readable text file - PHP doesn't care.
Now, as long as you just need to do basic processing of the string, you do not need to know the character encoding at all. So if you want to store the string back into a file using file_put_contents() or want to get its length (not the number of characters) using strlen(), you're fine.
However, as soon as you start doing more fancy string manipulation, you need to know the character encoding! There is no way to store it as part of the string, so you either have to track it separately, or, what most people do, use the convention of having all (text) strings in a common character encoding, like US-ASCII or nowadays UTF-8.
So because there is no way to set a character encoding for a string, PHP has no idea which character encoding the string is using. Due to that, the only sane thing for strlen() to do is to return the number of bytes, as this is the only thing PHP knows for sure.
If you provide the additional information of the used character encoding, you need to use another function - the function is called mb_strlen() in this case.
The same applies to preg_replace(): If you want to replace umlaut-a, or match three identical characters in a row, you need to know how umlaut-a is encoded, and in general, how characters are encoded.
So if you have a hypothetical character encoding, which encodes a lower-case a as a1 and an upper-case A as a2, a b as b1 and B as b2 (and so on), you can have an (encoded) string a1a1a1 which consists of three identical characters in a row. However, without knowing the encoding and by just looking at the byte sequence, there is no way to detect this.
Summary:
No sane 'default' is possible as PHP strings do not contain the character encoding. And even if, a single function like strlen() cannot return the length of the byte sequence as required for Content-Length HTTP header and at the same time the number of characters as useful to denote the length of a blog article.
That's why the Function Overloading Feature is inherently broken and even if it looks nice at first, will break your code in a hard-to-debug way.
multibyte => multi + byte.
1) It is use to work with string which is in other language(means not in English) format.
2) Default PHP string functions only work proper with English (or releted to it) language.
3) If you want to use strlen() or strpos() or uppercase() or strreplace() for special character,
Suppose We need to apply string functions on "Hello".
In chines (你好), Arabic (مرحبا), Japanese (こんにちは), Hindi (
नमस्ते), Gujarati (હેલો).
Different language can it's own character sets
so that mbstring introduced for communicate with various languages like (chines,Japanese etc).
Raul González is a perfect example of why:
It is about shortening too long user names for MySQL database, say we have 10 character limit and Raul González.
The unit test below is an example how you can get an error like this
General error: 1366 Incorrect string value: '\xC3' for column 'name' at row 1 (SQL: update users set name = Raul Gonz▒, updated_at = 2019-03-04 04:28:46 where id = 793)
and how you can avoid it
public function test_substr(): void
{
$name = 'Raul González';
$user = factory(User::class)->create(['name' => $name]);
try {
$name1 = substr($name, 0, 10);
$user->name = $name1;
$user->save();
} catch (Exception $ex) {
}
$this->assertTrue(isset($ex));
$name2 = mb_substr($name, 0, 10);
$user->name = $name2;
$user->save();
$this->assertTrue(true);
}
PHP Laravel and PhpUnit was used for illustration.
Hello
I am using class in javascript to hash string:
https://ssl.bsk.com.pl/mobi/js/sha1.js
hex_hmac_sha1("927545161", "asdasdasdasdś") ;
Result is:
5db0194c834d419fc5d68b72c88af1ac8ee749d6
In PHP i'm hashing:
echo hash_hmac('sha1', "asdasdasdasdś", '927545161');
but result is:
0b115775a20bed9922b6a9cc934cb5328fe71ade
Where is error?
5db0194c834d419fc5d68b72c88af1ac8ee749d6 != 0b115775a20bed9922b6a9cc934cb5328fe71ade
PHP interprets the UTF-8 string as sequence of 8-bit chars. Whereas in Javascript each character can resolve to an Unicode code point.
Your compacted and totally unreadable Javascript implementation uses .charCodeAt() to transform the string into a hexstring. I didn't bother to investigate it completely, but it's most likely that "ś".charCodeAt(0) simply resolves to 347, and the remainder of the conversion expected a value in the 8-bit range 0 to 255.