The <ctype.h> header file of the C Standard Library declares several functions that are useful for testing and mapping characters.
All the functions accepts int as a parameter, whose value must be EOF or representable as an unsigned char.
All the functions return non-zero (true) if the argument c satisfies the condition described, and zero(false) if not.
Library Functions
Following are the functions defined in the header ctype.h −
Sr.No. | Function & Description |
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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. |
The library also contains two conversion functions that accepts and returns an "int".