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GNU Info (mysql.info)Character arraysThe character definition arrays ------------------------------- `to_lower[]' and `to_upper[]' are simple arrays that hold the lowercase and uppercase characters corresponding to each member of the character set. For example: to_lower['A'] should contain 'a' to_upper['a'] should contain 'A' `sort_order[]' is a map indicating how characters should be ordered for comparison and sorting purposes. For many character sets, this is the same as `to_upper[]' (which means sorting will be case insensitive). MySQL will sort characters based on the value of `sort_order[character]'. For more complicated sorting rules, see the discussion of string collating below. Note: String collating. `ctype[]' is an array of bit values, with one element for one character. (Note that `to_lower[]', `to_upper[]', and `sort_order[]' are indexed by character value, but `ctype[]' is indexed by character value + 1. This is an old legacy to be able to handle EOF.) You can find the following bitmask definitions in `m_ctype.h': #define _U 01 /* Uppercase */ #define _L 02 /* Lowercase */ #define _N 04 /* Numeral (digit) */ #define _S 010 /* Spacing character */ #define _P 020 /* Punctuation */ #define _C 040 /* Control character */ #define _B 0100 /* Blank */ #define _X 0200 /* heXadecimal digit */ The `ctype[]' entry for each character should be the union of the applicable bitmask values that describe the character. For example, `'A'' is an uppercase character (`_U') as well as a hexadecimal digit (`_X'), so `ctype['A'+1]' should contain the value: _U + _X = 01 + 0200 = 0201 automatically generated by info2www version 1.2.2.9 |