As for the classification functions the ISO C standard also
generalizes the mapping functions. Instead of only allowing the two
standard mappings the locale can contain others. Again, the
localedef
program already supports generating such locale data
files.
wctrans
function.
wctrans
function has to be used to find out whether a named
mapping is defined in the current locale selected for the
LC_CTYPE
category. If the returned value is non-zero it can
afterwards be used in calls to towctrans
. If the return value is
zero no such mapping is known in the current locale.
Beside locale-specific mappings there are two mappings which are guaranteed to be available in every locale:
@multitable @columnfractions .5 .5
"tolower"
@tab "toupper"
This function is declared in `wctype.h'.
towctrans
function maps the input character wc
according to the rules of the mapping for which desc is an
descriptor and returns the so found value. The desc value must be
obtained by a successful call to wctrans
.
This function is declared in `wctype.h'.
wctrans
for them.
towlower
returns the corresponding
lower-case letter. If wc is not an upper-case letter,
wc is returned unchanged.
towlower
can be implemented using
towctrans (wc, wctrans ("tolower"))This function is declared in `wctype.h'.
towupper
returns the corresponding
upper-case letter. Otherwise wc is returned unchanged.
towupper
can be implemented using
towctrans (wc, wctrans ("toupper"))This function is declared in `wctype.h'.
char
type value to a wint_t
and use it as an
argument for towctrans
calls.
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