C&C++标准库学习-<ctype>-参考
int isalnum(int c);
int isalpha(int c);
int iscntrl(int c);
int isdigit(int c);
int isgraph(int c);
int islower(int c);
int isprint(int c);
int ispunct(int c);
int isspace(int c);
int isupper(int c);
int isxdigit(int c);
int tolower(int c);
int toupper(int c);
isalnum
int isalnum(int c);
The function returns nonzero if c is any of:
a b c d e f g h i j k l m n o p q r s t u v w x y z
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
0 1 2 3 4 5 6 7 8 9
or any other locale-specific alphabetic character.
isalpha
int isalpha(int c);
The function returns nonzero if c is any of:
a b c d e f g h i j k l m n o p q r s t u v w x y z
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
or any other locale-specific alphabetic character.
iscntrl
int iscntrl(int c);
The function returns nonzero if c is any of:
BEL BS CR FF HT NL VT
or any other implementation-defined control character.
isdigit
int isdigit(int c);
The function returns nonzero if c is any of:
0 1 2 3 4 5 6 7 8 9
isgraph
int isgraph(int c);
The function returns nonzero if c is any character for which either
isalnum or ispunct returns nonzero.
islower
int islower(int c);
The function returns nonzero if c is any of:
a b c d e f g h i j k l m n o p q r s t u v w x y z
or any other locale-specific lowercase character.
isprint
int isprint(int c);
The function returns nonzero if c is space or a character for which
isgraph returns nonzero.
ispunct
int ispunct(int c);
The function returns nonzero if c is any of:
! " # % & ' ( ) ; <
= > ? [ \ ] * + , -
. / : ^ _ { | } ~
or any other implementation-defined punctuation character.
isspace
int isspace(int c);
The function returns nonzero if c is any of:
CR FF HT NL VT space
or any other locale-specific space character.
isupper
int isupper(int c);
The function returns nonzero if c is any of:
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
or any other locale-specific uppercase character.
isxdigit
int isxdigit(int c);
The function returns nonzero if c is any of:
0 1 2 3 4 5 6 7 8 9 a b c d e f A B C D E F
tolower
int tolower(int c);
The function returns the corresponding lowercase letter if one exists
and if isupper(c); otherwise, it returns c.
toupper
int toupper(int c);
The function returns the corresponding uppercase letter if one exists
and if islower(c); otherwise, it returns c.
