
#include <ctype.h> int toupper(int c); int toupper_l(int c, locale_t locale);
For toupper(): The functionality described on this reference page is aligned with the ISO C standard. Any conflict between the requirements described here and the ISO C standard is unintentional. This volume of POSIX.1‐2017.
Upon successful completion, toupper() and toupper_l() shall return the uppercase letter corresponding to the argument passed; otherwise, they shall return the argument unchanged.
No errors are defined. The following sections are informative.
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setlocale(3p), uselocale(3p) The Base Definitions volume of POSIX.1‐2017, Chapter 7, Locale, ctype.h(0p), locale TOUPPER(3P)
Pages that refer to this page: ctype.h(0p), sort(1p), setlocale(3p), _toupper(3p)