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PHP: mb_strlen - Manual
mb_strlen
(PHP 4 >= 4.0.6, PHP 5, PHP 7, PHP 8)
mb_strlen — Get string length
Parameters
Return Values
Returns the number of characters in
string string having character encoding
encoding. A multi-byte character is
counted as 1.
Errors/Exceptions
If the encoding is unknown, an error of level
E_WARNING is generated.
Changelog
| Version | Description |
|---|---|
| 8.0.0 |
encoding is nullable now.
|
See Also
- mb_internal_encoding() - Set/Get internal character encoding
- grapheme_strlen() - Get string length in grapheme units
- iconv_strlen() - Returns the character count of string
- strlen() - Get string length
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User Contributed Notes 5 notes
Yzmir Ramirez ¶
14 years ago
drake127 ¶
18 years ago
Speed of mb_strlen varies a lot according to specified character set.
If you need length of string in bytes (strlen cannot be trusted anymore because of mbstring.func_overload) you should use <?php mb_strlen($string, '8bit'); ?>.
It's the fastest way (still a way slower than strlen, though) to determine byte length of string. Other single byte character sets (ASCII, ISO-8859-1, ...) are several times slower than 8bit.
koala at example dot com ¶
18 years ago
Just did a little benchmarking (1.000.000 times with lorem ipsum text) on the mbs functions
especially mb_strtolower and mb_strtoupper are really slow (up to 100 times slower compared to normal functions). Other functions are alike-ish, but sometimes up to 5 times slower.
just be cautious when using mb_ functions in high frequented scripts.
# test runs: 1000000
# benchmarking strlen vs. mb_strlen
# normal strlen: 3.6795361042023 ms, average: 3.6795361042023E-6 ms
# mb_strlen: 5.5934538841248 ms, average: 5.5934538841248E-6 ms
ok 1 - mb_strlen is slower than strlen
# mb_strlen is 1.52 slower than strlen
#
#
# benchmarking strpos vs. mb_strpos
# normal strpos: 5.5523281097412 ms, average: 5.5523281097412E-6 ms
# mb_strlen: 31.180974960327 ms, average: 3.1180974960327E-5 ms
ok 2 - mb_strlen is slower than strlen
# mb_strpos is 5.62 slower than strpos
#
#
# benchmarking substr vs. mb_substr
# normal substr: 3.4437320232391 ms, average: 3.4437320232391E-6 ms
# mb_strlen: 3.5374181270599 ms, average: 3.5374181270599E-6 ms
ok 3 - mb_strlen is slower than strlen
# mb_substr is 1.03 slower than substr
#
#
# benchmarking strtolower vs. mb_strtolower
# normal strtolower: 4.446839094162 ms, average: 4.446839094162E-6 ms
# mb_strlen: 193.44901108742 ms, average: 0.00019344901108742 ms
ok 4 - mb_strlen is slower than strlen
# mb_strtolower is 43.5 slower than strtolower
#
#
# benchmarking strtoupper vs. mb_strtoupper
# normal strtoupper: 3.0210740566254 ms, average: 3.0210740566254E-6 ms
# mb_strlen: 340.71775603294 ms, average: 0.00034071775603294 ms
ok 5 - mb_strlen is slower than strlen
# mb_strtoupper is 112.78 slower than strtoupper
Ben ¶
16 years ago
If you find yourself without the mb string functions and can't easily change it, a quick hack replacement for mb_strlen for utf8 characters is to use a a PCRE regex with utf8 turned on.
$strlen = preg_match_all("/.{1}/us",$utf8string,$dummy);
This is basically an ugly hack which counts all single character matches, and I'd expect it to be painfully slow on large strings.
David Spector ¶
5 years ago
It may not be clear whether PHP actually supports utf-8, which is the current de facto standard character encoding for Web documents, which supports most human languages. The good news is: it does.
I wrote a test program which successfully reads in a utf-8 file (without BOM) and manipulates the characters using mb_substr, mb_strlen, and mb_strpos (mb_substr should normally be avoided, as it must always start its search at character position 0).
The results with a variety of Unicode test characters in utf-8 encoding, up to four bytes in length, were mostly correct, except that accent marks were always mistakenly treated as separate characters instead of being combined with the previous character; this problem can be worked around by programming, when necessary.
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