Character classes

The preceding table shows the assignment of characters from the portable character set to character classes as defined by the LC_CTYPE category in the POSIX locale. The following additional character classes which represent supersets or subsets of those classes are also defined:

Character class	Scope
alpha	upper + lower
blank	subset of space: <blank> and <tab>
cntrl	control characters
digit	decimal characters
graph	alpha + digit + punct + space
lower	lowercase letters
print	alpha + digit + punct
punct	punctuation characters
space	white-space characters
tolower	mapping of uppercase letters to lowercase
toupper	mapping of lowercase letters to uppercase
upper	uppercase letters
xdigit	set of characters for hexadecimal representation: digit + A-F + a-f