C /C++标准库 - <cctype> (ctype.h)

1. 概述

This header declares a set of functions to classify and transform individual characters.

2. 函数

2.1 Character classification functions

序号	标签	原型	说明
1	isalnum	int isalnum ( int c );	判断字符c是不是十进制数字或字母
2	isalpha	int isalpha ( int c );	判断字符是否为字母
3	iscntrol	int iscntrl ( int c );	判断是否是控制字符
4	isblank(c++11)	int isblank ( int c );	判断是否为tab(‘\t’)或space(’ ‘)字符
5	isdigit	int isdigit ( int c );	Check if character is decimal digit
6	isgraph	int isgrapg ( int c );	Checks whether c is a character with graphical representation.(除空格之外的所有打印字符)
7	islower	int islower ( int c );	Checks whether c is a lowercase letter.
8	isupper	int isupper( int c )	Checks whether c is a uppercase letter.
9	isprint	int isprint ( int c );	Checks whether c is a printable character.
10	ispunct	int ispunct ( int c );	Checks whether c is a punctuation(标点符号） character.
11	isspace	int isspace ( int c );	Checks whether c is a white-space character.(包括空格’ ‘、换页’\f’、换行’\n’、回车’\r’、水平制表’\t’和垂直制表符’\v’)
12	isxdigit	int isxdigit ( int c );	Check if character is hexadecimal(十六进制）digit

2.2 Character conversion functions

序号	标签	原型	说明
1	tolower	int tolower ( int c );	Convert uppercase letter to lowercase
2	toupper	int toupper ( int c );	Convert lowercase letter to uppercase

3. 参考文献

1. http://www.cplusplus.com/reference/cctype/
2. 《C标准库》，P.J. Plauger 著