Xinu7/man/man3/ctype.3

.TH CTYPE 3
.SH NAME
ctype \- character type predicates and manipulation routines
.SH SYNOPSIS
.B #include <ctype.h>
.PP
.nf
.B isalpha(c)
.B ...
.B toascii(c)
.B tolower(c)
.B toupper(c)
.br
.B char c;
.SH DESCRIPTION
Routines beginning with \f2is\f1 are predicates that classify
the type of a character.
Routines beginning with \f2to\f1 convert characters.
Each predicate returns \f2TRUE\f1 if the condition is satisfied,
and \f2FALSE\f1 otherwise.
In the current implementation, predicates are macros that use table lookup
for efficiency.
.TP 15n
.I isalnum
.I c
is an alphanumeric character (i.e., a letter or digit)
.TP
.I isalpha
.I c
is a lower- or upper-case letter
.TP
.I isascii
.I c
is an ASCII character, code less than 0200
.TP
.I iscntrl
.I c
has a value less than octal 040 or is a DEL (octal value 0177).
.TP
.I isdigit
.I c
is a digit.
.TP
.I islower 
.I c
is a lower case letter.
.TP
.I isprint
.I c
is a printable character with octal value 040 (blank) through 0176 (tilde).
.TP
.I isprshort
.I c
is a printable short.
.TP
.I ispunct
.I c
is a punctuation character (neither control nor alphanumeric).
.TP
.I isspace
.I c
is a space, tab, carriage return, newline, or formfeed.
.TP
.I isupper
.I c
is an upper case letter.
.TP
.I isxdigit
.I c
is a hexadecimal digit (i.e., is 0\-9 or a-f).
.TP
.I toascii
Converts
.I c
to an ascii by turning off high-order bits.
.TP
.I tolower
Converts argument
.I c
from upper to lower case.
.TP
.I toupper
Converts argument
.I c
from lower to upper case.