The language parameter is the language code which consists of the two letter ISO 639 language code and an optional two letter ISO 3166 country code after a dash or underscore.

The language parameter is the language code which consists of the two letter ISO 639 language code and an optional two letter ISO 3166 country code after a dash or underscore.

Returns TRUE if every character in text is a lowercase letter in the current locale.

Returns TRUE if every character in text is a uppercase letter in the current locale.

Returns TRUE if every character in text is printable, but neither letter, digit or blank, FALSE otherwise.

This modifier turns on additional functionality of PCRE that is incompatible with Perl. Any backslash in a pattern that is followed by a letter that has no special meaning causes an error, thus reserving these combinations for future expansion. By default, as in Perl, a backslash followed by a letter with no special meaning is treated as a literal. There are at present no other features controlled by this modifier.

例如 见Whiteman 前注32 第508页(援引letter of the US State Department Legal advisor (Gross) to Richard Ränk Svenska Institutet För Internationall Rätt (Iohnson Institutet) Uppsala Sweden 29 January 1948 MS. Department of State file 500 12 1947)

Soundex keys have the property that words pronounced similarly produce the same soundex key, and can thus be used to simplify searches in databases where you know the pronunciation but not the spelling. This soundex function returns a string 4 characters long, starting with a letter.

This function performs the ROT13 encoding on the str argument and returns the resulting string. The ROT13 encoding simply shifts every letter by 13 places in the alphabet while leaving non alpha characters untouched. Encoding and decoding are done by the same function, passing an encoded string as argument will return the original version.