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<Runtime ConfigurationSummaries of supported encodings>
^Multibyte StringLast updated: Mon, 26 Oct 2026

Predefined Constants

The constants below are defined by this extension, and will only be available when the extension has either been compiled into PHP or dynamically loaded at runtime.

MB_OVERLOAD_MAIL (int)

Removed as of PHP 8.0.0.

MB_OVERLOAD_STRING (int)

Removed as of PHP 8.0.0.

MB_OVERLOAD_REGEX (int)

Removed as of PHP 8.0.0.

MB_CASE_UPPER (int)

Performs a full upper-case folding. This may change the length of the string. This is the mode used by mb_strtoupper().

MB_CASE_LOWER (int)

Performs a full lower-case folding. This may change the length of the string. This is the mode used by mb_strtolower().

MB_CASE_TITLE (int)

Performs a full title-case conversion based on the Cased and CaseIgnorable derived Unicode properties. In particular this improves handling of quotes and apostrophes. This may change the length of the string.

MB_CASE_FOLD (int)

Performs a full case fold conversion which removes case distinctions present in the string. This is used for caseless matching. This may change the length of the string. Available since PHP 7.3.

MB_CASE_LOWER_SIMPLE (int)

Performs a simple lower-case fold conversion. This does not change the length of the string. Available as of PHP 7.3.

MB_CASE_UPPER_SIMPLE (int)

Performs simple upper-case fold conversion. This does not change the length of the string. Available as of PHP 7.3.

MB_CASE_TITLE_SIMPLE (int)

Performs simple title-case fold conversion. This does not change the length of the string. Available as of PHP 7.3.

MB_CASE_FOLD_SIMPLE (int)

Performs a simple case fold conversion which removes case distinctions present in the string. This is used for caseless matching. This does not change the length of the string. Used by case-insensitive operations internally by the MBString extension. Available as of PHP 7.3.

MB_ONIGURUMA_VERSION (string)

The Oniguruma version, e.g. 6.9.4. Available as of PHP 7.4.


<Runtime ConfigurationSummaries of supported encodings>
^Multibyte StringLast updated: Mon, 26 Oct 2026