Defined in header <wctype.h>
wint_t towupper( wint_t wc );
(since C95)

Converts the given wide character to uppercase, if possible.


wc - wide character to be converted

Return value

Uppercase version of wc or unmodified wc if no uppercase version is listed in the current C locale.


Only 1:1 character mapping can be performed by this function, e.g. the uppercase form of 'ß' is (with some exceptions) the two-character string "SS", which cannot be obtained by towupper.

ISO 30112 specifies which pairs of Unicode characters are included in this mapping.


#include <stdio.h>
#include <wchar.h>
#include <wctype.h>
#include <locale.h>
int main(void)
    wchar_t wc =  L'\u017f'; // Latin small letter Long S ('ſ')
    printf("in the default locale, towupper(%#x) = %#x\n", wc, towupper(wc));
    setlocale(LC_ALL, "en_US.utf8");
    printf("in Unicode locale, towupper(%#x) = %#x\n", wc, towupper(wc));


in the default locale, towupper(0x17f) = 0x17f
in Unicode locale, towupper(0x17f) = 0x53


  • C11 standard (ISO/IEC 9899:2011):
    • The towupper function (p: 453)
  • C99 standard (ISO/IEC 9899:1999):
    • The towupper function (p: 399)

See also

converts a wide character to lowercase
converts a character to uppercase
C++ documentation for towupper

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