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islower(3) [bsd man page]

CTYPE(3)						     Library Functions Manual							  CTYPE(3)

NAME
isalpha, isupper, islower, isdigit, isxdigit, isalnum, isspace, ispunct, isprint, isgraph, iscntrl, isascii, toupper, tolower, toascii - character classification macros SYNOPSIS
#include <ctype.h> isalpha(c) . . . DESCRIPTION
These macros classify ASCII-coded integer values by table lookup. Each is a predicate returning nonzero for true, zero for false. Isascii and toascii are defined on all integer values; the rest are defined only where isascii is true and on the single non-ASCII value EOF (see stdio(3S)). isalpha c is a letter isupper c is an upper case letter islower c is a lower case letter isdigit c is a digit isxdigit c is a hex digit isalnum c is an alphanumeric character isspace c is a space, tab, carriage return, newline, vertical tab, or formfeed ispunct c is a punctuation character (neither control nor alphanumeric) isprint c is a printing character, code 040(8) (space) through 0176 (tilde) isgraph c is a printing character, similar to isprint except false for space. iscntrl c is a delete character(0177) or ordinary control character (less than 040). isascii c is an ASCII character, code less than 0200 tolower c is converted to lower case. Return value is undefined if not isupper(c). toupper c is converted to upper case. Return value is undefined if not islower(c). toascii c is converted to be a valid ascii character. SEE ALSO
ascii(7) 7th Edition May 12, 1986 CTYPE(3)

Check Out this Related Man Page

CTYPE(3)						     Library Functions Manual							  CTYPE(3)

NAME
isalpha, isupper, islower, isdigit, isxdigit, isalnum, isspace, ispunct, isprint, isgraph, iscntrl, isascii, toupper, tolower, toascii - character classification macros SYNOPSIS
#include <ctype.h> isalpha(c) . . . DESCRIPTION
These macros classify ASCII-coded integer values by table lookup. Each is a predicate returning nonzero for true, zero for false. Isascii and toascii are defined on all integer values; the rest are defined only where isascii is true and on the single non-ASCII value EOF (see stdio(3S)). isalpha c is a letter isupper c is an upper case letter islower c is a lower case letter isdigit c is a digit isxdigit c is a hex digit isalnum c is an alphanumeric character isspace c is a space, tab, carriage return, newline, vertical tab, or formfeed ispunct c is a punctuation character (neither control nor alphanumeric) isprint c is a printing character, code 040(8) (space) through 0176 (tilde) isgraph c is a printing character, similar to isprint except false for space. iscntrl c is a delete character(0177) or ordinary control character (less than 040). isascii c is an ASCII character, code less than 0200 tolower c is converted to lower case. Return value is undefined if not isupper(c). toupper c is converted to upper case. Return value is undefined if not islower(c). toascii c is converted to be a valid ascii character. SEE ALSO
ascii(7) 7th Edition May 12, 1986 CTYPE(3)

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