---
name: "ctype.h"
section: "3avr"
platform: "linux"
package: "avr-libc"
version: "1:2.2.1-1"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/ctype.h"
---

# ctype.h(3avr)

## NAME

ctype.h

## SYNOPSIS

### Functions

**Character classification routines**\
 These functions perform character classification. They return true or false status depending whether the character passed to the function falls into the function's classification (i.e. **isdigit()** returns true if its argument is any value '0' though '9', inclusive). If the input is not an unsigned char value, all of this function return false.

int **isalnum** (int \_\_c)\
 int **isalpha** (int \_\_c)\
 int **isascii** (int \_\_c)\
 int **isblank** (int \_\_c)\
 int **iscntrl** (int \_\_c)\
 int **isdigit** (int \_\_c)\
 int **isgraph** (int \_\_c)\
 int **islower** (int \_\_c)\
 int **isprint** (int \_\_c)\
 int **ispunct** (int \_\_c)\
 int **isspace** (int \_\_c)\
 int **isupper** (int \_\_c)\
 int **isxdigit** (int \_\_c)\

**Character convertion routines**\
 This realization permits all possible values of integer argument. The **toascii()** function clears all highest bits. The **tolower()** and **toupper()** functions return an input argument as is, if it is not an unsigned char value.

int **toascii** (int \_\_c)\
 int **tolower** (int \_\_c)\
 int **toupper** (int \_\_c)\

## Author

Generated automatically by Doxygen for AVR-LibC from the source code.