tolower(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)

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)