C in a Nutshell

Name

tolower

Synopsis

Converts an uppercase alphabetic character to lowercase

#include <ctype.h>
inttolower( int c );

The tolower() function returns the lowercase letter corresponding to the character value of its argument c. If c is not an uppercase letter, or if there is no lowercase letter which corresponds to it, its value is returned unchanged.

Tip

Which characters are considered uppercase, and which of those have a corresponding lowercase character, depends on the current locale setting for the localization category LC_CTYPE, which you can query or change using the setlocale() function. The uppercase characters are those for which isupper() returns true; the lowercase characters are those for which islower() returns true.

Accented characters, umlauts, and the like are considered alphabetic only in certain locales. Moreover, other locales may have characters that are alphabetic, but are neither upper- nor lowercase, or both upper- and lowercase.

Example

See the examples at getchar() and setlocale() in this chapter.

See Also

islower(), toupper(), isupper(), towupper(), towlower(), towctrans()