Wide character

Wide character is a computer programming term. It is a vague term used to represent a datatype that is richer than the traditional (8-bit) characters. It is not the same thing as Unicode.

wchar_t is a data type in ANSI/ISO C, ANSI/ISO C++, and some other programming languages that is intended to represent wide characters.

The Unicode standard 4.0 says that

"ANSI/ISO C leaves the semantics of the wide character set to the specific implementation but requires that the characters from the portable C execution set correspond to their wide character equivalents by zero extension."

and that

"The width of wchar_t is compiler-specific and can be as small as 8 bits. Consequently, programs that need to be portable across any C or C++ compiler should not use wchar_t for storing Unicode text. The wchar_t type is intended for storing compiler-defined wide characters, which may be Unicode characters in some compilers."

Under Win32, wchar_t is 16 bits wide and represents a UTF-16 code unit. On Unix-like systems wchar_t is commonly 32 bits wide and represents a UTF-32 code unit.

In ANSI C library header files, <wchar.h> and <wctype.h> deal with the wide characters.

Functions

There are several functions in C's stdlib.h to help with wchar_t's.

• wctomb() - wide char to multibyte char
• mbtowc() - multibyte char to wide char
• wcstombs() - wide-char string to multibyte-char string
• mbstowcs() - multibyte-char string to wide-char string
• mblen() - number of bytes in a multibyte char

External links

• The Unicode Standard, Version 4.0 - online edition