#include <wctype.h> wint_t towctrans(wint_t wc, wctrans_t desc);
The towctrans() function maps the wide character wc using the mapping described by desc. The current setting of the LC_CTYPE category shall be the same as during the call to wctrans() that returned the value desc.
The function call towctrans(wc, wctrans("tolower")) behaves the same as towlower(wc).
The function call towctrans(wc, wctrans("toupper")) behaves the same as towupper(wc).
The towctrans() function returns the mapped value of wc, using the mapping described by desc; otherwise, it returns wc unchanged.
See attributes(5) for descriptions of the following attributes: