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📜  C库-

📅  最后修改于: 2020-12-19 05:36:37             🧑  作者: Mango

C标准库的ctype.h头文件声明了几个对测试和映射字符有用的函数。

所有函数均接受int作为参数，其值必须为EOF或可表示为无符号字符。

如果参数c满足所描述的条件，则所有函数均返回非零(true)，否则返回零(false)。

库功能

以下是标头ctype.h中定义的函数-

Sr.No. Function & Description
1 int isalnum(int c)

This function checks whether the passed character is alphanumeric.
2 int isalpha(int c)

This function checks whether the passed character is alphabetic.
3 int iscntrl(int c)

This function checks whether the passed character is control character.
4 int isdigit(int c)

This function checks whether the passed character is decimal digit.
5 int isgraph(int c)

This function checks whether the passed character has graphical representation using locale.
6 int islower(int c)

This function checks whether the passed character is lowercase letter.
7 int isprint(int c)

This function checks whether the passed character is printable.
8 int ispunct(int c)

This function checks whether the passed character is a punctuation character.
9 int isspace(int c)

This function checks whether the passed character is white-space.
10 int isupper(int c)

This function checks whether the passed character is an uppercase letter.
11 int isxdigit(int c)

This function checks whether the passed character is a hexadecimal digit.

该库还包含两个转换函数，它们接受并返回一个“ int”。

Sr.No. Function & Description
1 int tolower(int c)

This function converts uppercase letters to lowercase.
2 int toupper(int c)

This function converts lowercase letters to uppercase.

字符类

Sr.No. Character Class & Description
1

Digits

This is a set of whole numbers { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 }.
2

Hexadecimal digits

This is the set of { 0 1 2 3 4 5 6 7 8 9 A B C D E F a b c d e f }.
3

Lowercase letters

This is a set of lowercase letters { 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 }.
4

Uppercase letters

This is a set of uppercase letters {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 }.
5

Letters

This is a set of lowercase and uppercase letters.
6

Alphanumeric characters

This is a set of Digits, Lowercase letters and Uppercase letters.
7

Punctuation characters

This is a set of ! ” # $ % & ‘ ( ) * + , – . / : ; < = > ? @ [ \ ] ^ _ ` { | } ~
8

Graphical characters

This is a set of Alphanumeric characters and Punctuation characters.
9

Space characters

This is a set of tab, newline, vertical tab, form feed, carriage return, and space.
10

Printable characters

This is a set of Alphanumeric characters, Punctuation characters and Space characters.
11

Control characters

In ASCII, these characters have octal codes 000 through 037, and 177 (DEL).
12

Blank characters

These are spaces and tabs.
13

Alphabetic characters

This is a set of Lowercase letters and Uppercase letters.