mb-scrub
mb_scrub
Replace ill-formed byte sequences with the substitute character
ENTITY
string
mb_scrub
string
string
string
null
encoding
ENTITY
Perform a character set conversion from the specified encoding, or the default encoding if no encoding was specified, to the same encoding. This has the effect of replacing any invalid byte sequences with the substitute character.
ENTITY
string
The input string.
encoding
The encoding used to interpret string. If it is omitted or ENTITY, the mbstring.internal_encoding setting will be used if set, otherwise the default_charset setting will be used.
ENTITY
The ENTITY result with invalid byte sequences replaced.
ENTITY ENTITY
ENTITY
| ENTITY | ENTITY |
|---|
ENTITY
Byte-level replacement performed by mb_scrub
bin2hex is used here because terminals, browsers and fonts may render an ill-formed byte sequence with a replacement character of their own, which hides what the string actually contains.
<?php
// The byte 0xFF cannot appear in a valid UTF-8 string.
$input = "A\xFFB";
echo bin2hex($input), "\n";
// The default substitute character is "?" (0x3F).
echo bin2hex(mb_scrub($input, 'UTF-8')), "\n";
// U+FFFD REPLACEMENT CHARACTER is encoded as EF BF BD in UTF-8.
mb_substitute_character(0xFFFD);
echo bin2hex(mb_scrub($input, 'UTF-8')), "\n";
?>
ENTITY
41ff42
413f42
41efbfbd42
Using mb_scrub before UTF-8 aware processing
PCRE patterns using the u modifier reject subjects that are not well-formed UTF-8. Scrubbing the input first makes it acceptable.
<?php
$input = "A\xFFB";
var_dump(preg_match_all('/./us', $input));
echo preg_last_error_msg(), "\n";
$clean = mb_scrub($input, 'UTF-8');
var_dump(preg_match_all('/./us', $clean));
?>
ENTITY
bool(false)
Malformed UTF-8 characters, possibly incorrectly encoded
int(3)
ENTITY
mb_substitute_character
mb_check_encoding
mb_convert_encoding
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