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
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 |