TOUPPERSection: Linux Programmer's Manual (3 )
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NAMEtoupper, tolower - convert letter to upper or lower case
#include <ctype.h> int toupper (int c); int tolower (int c);
DESCRIPTIONtoupper() converts the letter c to upper case, if possible.
tolower() converts the letter c to lower case, if possible.
RETURN VALUEThe value returned is that of the converted letter, or c if the conversion was not possible.
CONFORMING TOANSI C, BSD 4.3
BUGSThe details of what constitutes an uppercase or lowercase letter depend on the current locale. For example, the default C locale does not know about umlauts, so no conversion is done for them.
SEE ALSOisalpha(3), setlocale(3), locale(7)
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Time: 07:04:05 GMT, May 26, 2022