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man pages section 3: Basic Library Functions

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Updated: Thursday, June 13, 2019
 
 

tolower(3C)

Name

tolower, tolower_l - transliterate upper-case characters to lower-case

Synopsis

#include <ctype.h> 

int tolower(int c);
int tolower_l(int, locale_t locale);

Description

The tolower() and tolower_l() functions have as a domain a type int, the value of which is representable as an unsigned char or the value of EOF. If the argument has any other value, the argument is returned unchanged. If the argument of tolower() or tolower_l() represents an upper-case letter, and there exists a corresponding lower-case letter as defined by character type information in the current or in the locale represented by locale, respectively (category LC_CTYPE), the result is the corresponding lower-case letter. All other arguments in the domain are returned unchanged.

The behavior is undefined if the locale argument to tolower_l() is the special locale object LC_GLOBAL_LOCALE or is not a valid locale object handle.

Return Values

On successful completion, tolower() and tolower_l() return the lower-case letter corresponding to the argument passed. Otherwise, it returns the argument unchanged.

Errors

No errors are defined.

Attributes

See attributes(7) for descriptions of the following attributes:

ATTRIBUTE TYPE
ATTRIBUTE VALUE
CSI
Enabled
Interface Stability
Standard
MT-Level
MT-Safe

See Also

_tolower(3C), duplocale(3C), freelocale(3C), newlocale(3C), setlocale(3C), uselocale(3C), attributes(7), standards(7)