ctype h library: The ctype.h header file includes numerous C standard library functions that declares several functions used for classify and transform individual characters.
All functions of this library take a character as argument, we can either call individual character or their corresponding ASCII value(as int). All classification functions return non-zero value(true) if character satisfies the condition, otherwise zero(false).
Transformation functions takes a character as argument and returns a character after transforming it. The tolower and toupper are the only transformation functions of ctype.h header file.
List of ctype Library Functions
ctype.h functions: Click on function names below to see detailed description of functions.
| Function | Description |
|---|---|
| isalnum | It checks whether a character is an alphanumeric character or not |
| isalpha | It checks whether a character is an alphabet or not |
| iscntrl | It checks whether a character is control character or not |
| isdigit | It checks whether a character is decimal digit character or not |
| isgraph | It checks whether a character has graphical representation or not |
| islower | It checks whether a character is lowercase alphabet or not |
| isprint | It checks whether a character is printable character or not |
| ispunct | It checks whether a character is punctuation character or not |
| isspace | It checks whether a character is white-space character or not |
| isupper | It checks whether a character is uppercase alphabet or not |
| tolower | It converts an uppercase alphabet to a lowercase alphabet |
| toupper | It converts a lowercase alphabet to an uppercase alphabet |