This question already has answers here:
PHP: strlen returns character length instead of byte length
(5 answers)
Closed 9 years ago.
I am trying to get the length of this unicode characters string
$text = 'نام سلطان م';
$length = strlen($text);
echo $length;
output
20
How it determines the length of unicode characters string?
strlen() is not handling multibyte characters correctly, as it assumes 1 char equals 1 byte, which is simply invalid for unicode. This behavior is clearly documented:
strlen() returns the number of bytes rather than the number of characters in a string.
The solution is to use mb_strlen() function instead (mb stands for multi byte) (see mb_strlen() docs).
EDIT
If for any reason change in code is not possible/doable, one may want to ensure string functions are automatically overloaded by multi-byte counterparts:
To use function overloading, set mbstring.func_overload in php.ini to
a positive value that represents a combination of bitmasks specifying
the categories of functions to be overloaded. It should be set to 1 to
overload the mail() function. 2 for string functions, 4 for regular
expression functions. For example, if it is set to 7, mail, strings
and regular expression functions will be overloaded.
This is supported by PHP and documented here (note this feature is deprecated in PHP 7.2 and newer).
Please note that you may also need to edit your php.ini to ensure mb_string module is enabled. Available settings are documented here.
You are looking for mb_strlen.
Function strlnen does not count the number of characters, but the number of bytes. For multibyte characters it will return higher numbers.
Use mb_strlen() instead to count the actual count of characters.
Just as an addendum to the other answers that reference mb_strlen():
If the php.in setting mbstring.func_overload has bit 2 set to 1, then strlen will count characters based on the default charset; otherwise it will count the number of bytes in the string
Related
This question already has answers here:
utf8 string length
(2 answers)
Closed 4 years ago.
I want to create inputs in html5 with a maxlength.
I have a text and I have to transform into a form with inputs. The maxlength of inputs are defined into the text. But with the £ characters strlen returns 2.
Does somebody know why please?
$strTEST = "£";
$i = strlen($strTEST);
var_dump($i); // display 2
From: http://php.net/strlen
Note:
strlen() returns the number of bytes rather than the number of
characters in a string.
If you go to http://www.utf8-chartable.de/ and search for £:
Unicode code point character hex name
U+00A3 £ c2 a3 POUND SIGN
You can see the hex representations needs two bytes to store this specific character.
An alternative solution to circumvent this problem would be using mb_strlen
From: http://php.net/mb_strlen
Returns the number of characters in string str having character
encoding encoding. A multi-byte character is counted as 1.
I would like to prepare simple regular expression for php's uniqid. I checked uniqid manual looking for set of chars used as return value. But the documentation only mention that:
#return string the unique identifier, as a string.
And
With an empty prefix, the returned string will be 13 characters long. If more_entropy is true, it will be 23 characters.
I would like to know what characters can I expect in the return value. Is it a hex string? How to know for sure? Where to find something more about the uniqid function?
The documentation doesn't specify the string contents; only its length. Generally, you shouldn't depend on it. If you print the value between a pair of delimiters, like quotation marks, you could use them in the regular expression:
"([^"]+)" ($1 contains the value)
As long as you develop for a particular PHP version, you can inspect its implementation and assume, that it doesn't change. If you upgrade, you should check, if the assumption is still valid.
A comment in uniqid documentation describes, that it is essentially a hexadecimal number with an optional numeric suffix:
if (more_entropy) {
uniqid = strpprintf(0, "%s%08x%05x%.8F", prefix, sec, usec, php_combined_lcg() * 10);
} else {
uniqid = strpprintf(0, "%s%08x%05x", prefix, sec, usec);
}
Which gives you two possible output formats:
uniqid() - 13 characters, hexadecimal number
uniqid('', true) - 14 - 23 characters, hexadecimal number with floating number suffix
computed elsewhere
If you use other delimiters than alphanumeric characters and dot, you could use one of these simple regular expressions to grab the value in either of the two formats:
[0-9a-f]+
[.0-9a-f]+
If you need 100% format guarantee for any PHP version, you could write your own function based on sprintf.
I admit, that it is unlikely, that the uniqid would significantly change; I would expect creating other extensions to provide different formats. Another comment in uniqid documentation shows a RFC 4211 compliant UUID implementation. There was also a discussion on stackoverflow about it.
I found this on the php site: http://www.php.net/manual/en/function.uniqid.php#95001
If this is to be believed then the 13 character version is entirely hex.
However the 23 character version has:
14 characters (hex)
then a dot
then another 8 characters (decimal)
If you need to be entirely sure, you can verify this yourself: http://sandbox.onlinephpfunctions.com/code/c04c7854b764faee2548180eddb8c23288dcb5f7
I have this code:
$string = 'علی';
echo strlen($string);
Since $string has 3 Persian characters, output must be 3 but I get 6.
علی has 3 characters. Why my output is 6 ?
How can I use strlen() in php for Persian with real output?
Use mb_strlen
Returns the number of characters in string str having character encoding (the second parameter) encoding. A multi-byte character is counted as 1.
Since your 3 characters are all multi-byte, you get 6 returned with strlen, but this returns 3 as expected.
echo mb_strlen($string,'utf-8');
Fiddle
Note
It's important not to underestimate the power of this method and any similar alternatives. For example one could be inclined to say ok if the characters are multi-byte then just get the length with strlen and divide it by 2 but that will only work if all characters of your string are multi-byte and even a period . will invalidate the count. For example this
echo mb_strlen('علی.','utf-8');
Returns 4 which is correct. So this function is not only taking the whole length and dividing it by 2, it counts 1 for every multi-byte character and 1 for every single-byte character.
Note2:
It looks like you decided not to use this method because mbstring extension is not enabled by default for old PHP versions and you might have decided not to try enabling it:) For future readers though, it is not difficult and its advisable to enable it if you are dealing with multi-byte characters as its not only the length that you might need to deal with. See Manual
try this:
function ustrlen($text)
{
if(function_exists('mb_strlen'))
return mb_strlen( $text , 'utf-8' );
return count(preg_split('//u', $text)) - 2;
}
it will work for any php version.
mb_strlen function is your friend
$string = 'علی';
echo mb_strlen($string, 'utf8');
As of PHP5, iconv_strlen() can be used (as described in php.net, it returns the character count of a string, so probably it's the best choice):
iconv_strlen("علی");
// 3
Based on this answer by chernyshevsky#hotmail.com, you can try this:
function string_length (string $string) : int {
return strlen(utf8_decode($string));
}
string_length("علی");
// 3
Also, as others answered, you can use mb_strlen():
mb_strlen("علی");
// 3
Notes
There is a very little difference between them (for illegal latin characters):
iconv_strlen("a\xCC\r"); // A notice
string_length("a\xCC\r"); // 3
mb_strlen("a\xCC\r"); // 2
Performance: mb_strlen() is the fastest. Totally, there is no difference between iconv_strlen() and string_length() at performance. But amazingly, mb_strlen() is faster that both about 9 times (as I tested)!
When I try to str_pad() with zero on a hebrew word, it doesn't add the required amount of zeros.
For example:
$word='שלום';
$str=str_pad($word,10,' ',STR_PAD_RIGHT);
The result:
שלום00
str_pad(...) is not multibyte safe. This means that, since you're using 4 2-byte characters, that functions sees that the string length is 8, therefore only 2 zeros will be used for padding.
I've spotted this user-contributed function inside the PHP manual. It's untested and use at your own risk, but it seems to me that's what you're looking for.
function mb_str_pad ($input, $pad_length, $pad_string, $pad_style, $encoding="UTF-8") {
return str_pad($input,
strlen($input)-mb_strlen($input,$encoding)+$pad_length,
$pad_string, $pad_style);
}
I want to use str_word_count() on a UTF-8 string.
Is this safe in PHP? It seems to me that it should be (especially considering that there is no mb_str_word_count()).
But on php.net there are a lot of people muddying the water by presenting their own 'multibyte compatible' versions of the function.
So I guess I want to know...
Given that str_word_count simply counts all character sequences in delimited by " " (space), it should be safe on multibyte strings, even though its not necessarily aware of the character sequences, right?
Are there any equivalent 'space' characters in UTF-8, which are not ASCII " " (space)?#
This is where the problem might lie I guess.
I'd say you guess right. And indeed there are space characters in UTF-8 which are not part of US-ASCII. To give you an example of such spaces:
Unicode Character 'NO-BREAK SPACE' (U+00A0): 2 Bytes in UTF-8: 0xC2 0xA0 (c2a0)
And perhaps as well:
Unicode Character 'NEXT LINE (NEL)' (U+0085): 2 Bytes in UTF-8: 0xC2 0x85 (c285)
Unicode Character 'LINE SEPARATOR' (U+2028): 3 Bytes in UTF-8: 0xE2 0x80 0xA8 (e280a8)
Unicode Character 'PARAGRAPH SEPARATOR' (U+2029): 3 Bytes in UTF-8: 0xE2 0x80 0xA8 (e280a8)
Anyway, the first one - the 'NO-BREAK SPACE' (U+00A0) - is a good example as it is also part of Latin-X charsets. And the PHP manual already provides a hint that str_word_count would be locale dependent.
If we want to put this to a test, we can set the locale to UTF-8, pass in an invalid string containing a \xA0 sequence and if this still counts as word-breaking character, that function is clearly not UTF-8 safe, hence not multibyte safe (as same non-defined as per the question):
<?php
/**
* is PHP str_word_count() multibyte safe?
* #link https://stackoverflow.com/q/8290537/367456
*/
echo 'New Locale: ', setlocale(LC_ALL, 'en_US.utf8'), "\n\n";
$test = "aword\xA0bword aword";
$result = str_word_count($test, 2);
var_dump($result);
Output:
New Locale: en_US.utf8
array(3) {
[0]=>
string(5) "aword"
[6]=>
string(5) "bword"
[12]=>
string(5) "aword"
}
As this demo shows, that function totally fails on the locale promise it gives on the manual page (I do not wonder nor moan about this, most often if you read that a function is locale specific in PHP, run for your life and find one that is not) which I exploit here to demonstrate that it by no means does anything regarding the UTF-8 character encoding.
Instead for UTF-8 you should take a look into the PCRE extension:
Matching Unicode letter characters in PCRE/PHP
PCRE has a good understanding of Unicode and UTF-8 in PHP in specific. It can also be quite fast if you craft the regular expression pattern carefully.
About the "template answer" - I don't get the demand "working faster". We're not talking about long times or lot of counts here, so who cares if it takes some milliseconds longer or not?
However, a str_word_count working with soft hyphen:
function my_word_count($str) {
return str_word_count(str_replace("\xC2\xAD",'', $str));
}
a function that complies with the asserts (but is probably not faster than str_word_count):
function my_word_count($str) {
$mystr = str_replace("\xC2\xAD",'', $str); // soft hyphen encoded in UTF-8
return preg_match_all('~[\p{L}\'\-]+~u', $mystr); // regex expecting UTF-8
}
The preg function is essentially the same what's already proposed, except that a) it already returns a count so no need to supply matches, which should make it faster and b) there really should not be iconv fallback, IMO.
About a comment:
I can see that your PCRE functions are wrost (performance) than my
preg_word_count() because need a str_replace that you not need:
'~[^\p{L}\'-\xC2\xAD]+~u' works fine (!).
I considered that a different thing, string replace will only remove the multibyte character, but regex of yours will deal with \\xC2 and \\xAD in any order they might appear, which is wrong. Consider a registered sign, which is \xC2\xAE.
However, now that I think about it due to the way valid UTF-8 works, it wouldn't really matter, so that should be usable equally well. So we can just have the function
function my_word_count($str) {
return preg_match_all('~[\p{L}\'\-\xC2\xAD]+~u', $str); // regex expecting UTF-8
}
without any need for matches or other replacements.
About str_word_count(str_replace("\xC2\xAD",'', $str));, if is stable
with UTF8, is good, but seems is not.
If you read this thread, you'll know str_replace is safe if you stick to valid UTF-8 strings. I didn't see any evidence in your link of the contrary.
EDITED (to show new clues): there are a possible solution using str_word_count() with PHP v5.1!
function my_word_count($str, $myLangChars="àáãâçêéíîóõôúÀÁÃÂÇÊÉÍÎÓÕÔÚ") {
return str_word_count($str, 0, $myLangChars);
}
but not is 100% because I try to add to $myLangChars \xC2\xAD (the SHy - SOFT HYPHEN character), that must be a word component in any language, and it not works (see).
Another, not so fast, but complete and flexible solution (extracted from here), based on PCRE library, but with an option to mimic the str_word_count() behaviour on non-valid-UTF8:
/**
* Like str_word_count() but showing how preg can do the same.
* This function is most flexible but not faster than str_word_count.
* #param $wRgx the "word regular expression" as defined by user.
* #param $triggError changes behaviour causing error event.
* #param $OnBadUtfTryAgain when true mimic the str_word_count behaviour.
* #return 0 or positive integer as word-count, negative as PCRE error.
*/
function preg_word_count($s,$wRgx='/[-\'\p{L}\xC2\xAD]+/u', $triggError=true,
$OnBadUtfTryAgain=true) {
if ( preg_match_all($wRgx,$s,$m) !== false )
return count($m[0]);
else {
$lastError = preg_last_error();
$chkUtf8 = ($lastError==PREG_BAD_UTF8_ERROR);
if ($OnBadUtfTryAgain && $chkUtf8)
return preg_word_count(
iconv('CP1252','UTF-8',$s), $wRgx, $triggError, false
);
elseif ($triggError) trigger_error(
$chkUtf8? 'non-UTF8 input!': "error PCRE_code-$lastError",
E_USER_NOTICE
);
return -$lastError;
}
}
(TEMPLATE ANSWER) help for bounty!
(this is not an answer, is a help for bounty, because I can not edit neither to duplicate the question)
We want to count "real-world words" in a UTF-8 latim text.
FOR BOUNTY, WE NEED:
a function that comply the asserts below and is faster than str_word_count;
or str_word_count working with SHy character (how to?);
or preg_word_count working faster (using preg_replace? word-separator regular expression?).
ASSERTS
Supose that a "multibyte safe" function my_word_count() exists, then the following asserts must be true:
assert_options(ASSERT_ACTIVE, 1);
$text = "1,2,3,4=0 (1 2 3 4)=0 (... ,.)=0 (2.5±0.1; 0.5±0.2)=0";
assert( my_word_count($text)==0 ); // no word there
$text = "(one two,three;four)=4 (five-six se\xC2\xADven)=2";
assert( my_word_count($text)==6 ); // hyphen merges two words
$text = "(um±dois três)=3 (àáãâçêéíîóõôúÀÁÃÂÇÊÉÍÎÓÕÔÚ)=1";
assert( my_word_count($text)==4 ); // a UTF8 case
$text = "(ÍSÔ9000-X, ISÔ 9000-X, ÍSÔ-9000-X)=6"; //Codes are words?
assert( my_word_count($text)==6 ); // suppose no: X is another word
All it does it count the number of spaces, or words in between. if you're curious, you can just make your own counting function using explode and count.
Anytime the ascii space byte is found, it splits and that all there really is to it.