For processing strings of such characters, it is more efficient to convert these codes into a uniform-length representation. This converted form is intended for internal processing of characters. The internal representation of data is referred to as the process code or wide character code representation of the character. A multibyte subroutine uses multibyte character sets. A wide character subroutine uses wide character sets.
Multibyte subroutines have an mb prefix.
Wide character subroutines have a wc prefix. The corresponding string-handling subroutines are indicated by the mbs and wcs prefixes, respectively. Deciding when to use multibyte or wide character subroutines can be made only after careful analysis. If a program primarily uses multibyte subroutines, it may be necessary to convert the multibyte character codes to wide character codes to use certain wide character subroutines. If a program uses wide character subroutines, data may need to be converted to multibyte form for invoking subroutines.