(PHP 4 >= 4.0.6, PHP 5, PHP 7, PHP 8)
mb_detect_encoding — Detect character encoding
mb_detect_encoding(string $string, array|string|null $encodings = null, bool $strict = false): string|false
Detects the most likely character encoding for string string from a list of candidates.
As of PHP 8.1 this function uses heuristics to detect which of the valid text encodings in the specified list is most likely to be correct and may not be in order of encodings provided.
Automatic detection of the intended character encoding can never be entirely reliable; without some additional information, it is similar to decoding an encrypted string without the key. It is always preferable to use an indication of character encoding stored or transmitted with the data, such as a "Content-Type" HTTP header.
This function is most useful with multibyte encodings, where not all sequences of bytes form a valid string. If the input string contains such a sequence, that encoding will be rejected.
The name of this function is misleading, it performs "guessing" rather than "detection".
The guesses are far from accurate, and therefore you cannot use this function to accurately detect the correct character encoding.
stringThe string being inspected.
encodingsA list of character encodings to try. The list may be specified as an array of strings, or a single string separated by commas.
If encodings is omitted or null, the current detect_order (set with the mbstring.detect_order configuration option, or mb_detect_order() function) will be used.
strict Controls the behaviour when string is not valid in any of the listed encodings. If strict is set to false, the closest matching encoding will be returned; if strict is set to true, false will be returned.
The default value for strict can be set with the mbstring.strict_detection configuration option.
The detected character encoding, or false if the string is not valid in any of the listed encodings.
| Version | Description |
|---|---|
| 8.2.0 | mb_detect_encoding() will no longer return the following non text encodings: "Base64", "QPrint", "UUencode", "HTML entities", "7 bit" and "8 bit". |
Example #1 mb_detect_encoding() example
<?php $str = "\x95\xB6\x8E\x9A\x83\x52\x81\x5B\x83\x68"; // Detect character encoding with current detect_order var_dump(mb_detect_encoding($str)); // "auto" is expanded according to mbstring.language var_dump(mb_detect_encoding($str, "auto")); // Specify "encodings" parameter by list separated by comma var_dump(mb_detect_encoding($str, "JIS, eucjp-win, sjis-win")); // Use array to specify "encodings" parameter $encodings = [ "ASCII", "JIS", "EUC-JP" ]; var_dump(mb_detect_encoding($str, $encodings)); ?>
The above example will output:
string(5) "ASCII" string(5) "ASCII" string(8) "SJIS-win" string(5) "ASCII"
Example #2 Effect of strict parameter
<?php // 'áéóú' encoded in ISO-8859-1 $str = "\xE1\xE9\xF3\xFA"; // The string is not valid ASCII or UTF-8, but UTF-8 is considered a closer match var_dump(mb_detect_encoding($str, ['ASCII', 'UTF-8'], false)); var_dump(mb_detect_encoding($str, ['ASCII', 'UTF-8'], true)); // If a valid encoding is found, the strict parameter does not change the result var_dump(mb_detect_encoding($str, ['ASCII', 'UTF-8', 'ISO-8859-1'], false)); var_dump(mb_detect_encoding($str, ['ASCII', 'UTF-8', 'ISO-8859-1'], true)); ?>
The above example will output:
string(5) "UTF-8" bool(false) string(10) "ISO-8859-1" string(10) "ISO-8859-1"
In some cases, the same sequence of bytes may form a valid string in multiple character encodings, and it is impossible to know which interpretation was intended. For instance, among many others, the byte sequence "\xC4\xA2" could be:
Example #3 Effect of order when multiple encodings match
<?php $str = "\xC4\xA2"; // The string is valid in all three encodings, but the first one listed may not always be the one returned var_dump(mb_detect_encoding($str, ['UTF-8'])); var_dump(mb_detect_encoding($str, ['UTF-8', 'ISO-8859-1', 'ISO-8859-5'])); // as of php8.1 this returns ISO-8859-1 instead of UTF-8 var_dump(mb_detect_encoding($str, ['ISO-8859-1', 'ISO-8859-5', 'UTF-8'])); var_dump(mb_detect_encoding($str, ['ISO-8859-5', 'UTF-8', 'ISO-8859-1'])); ?>
The above example will output:
string(5) "UTF-8" string(10) "ISO-8859-1" string(10) "ISO-8859-1" string(10) "ISO-8859-5"
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https://www.php.net/manual/en/function.mb-detect-encoding.php