---
name: "Char.Ascii"
section: "3o"
platform: "linux"
package: "ocaml"
version: "5.5.0-1"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/Char.Ascii"
---

# Char.Ascii(3o)

ASCII character set support.

## NAME

Char.Ascii - ASCII character set support.

## Module

Module   Char.Ascii

## Documentation

Module **Ascii**\
  :  **sig end**

ASCII character set support.

These functions give meaning to the integers \[ **0x00** ; **0x7F** \] of the ASCII character set.

Since the UTF-8 encoding of Unicode has the same encoding and character semantics (U+0000 to U+001F) for these bytes, the functions can be safely used on elements of UTF-8 encoded  **string** and  **bytes** values. However the functions only deal with ASCII related matters. For example the notion of Unicode whitespace is much larger than the ASCII whitespace determined by **Char.Ascii.is\_white** .

**Since** 5.4

### Characters

*val min* :  **char**

**min** is  **'\\x00'** .

*val max* :  **char**

**max** is  **'\\x7F'** .

### Predicates

*val is\_valid* :  **char -\> bool**

**is\_valid c** is  **true** if and only if  **c** is an ASCII character, that is a byte in the range \[ **Char.Ascii.min** ; **Char.Ascii.max** \].

*val is\_upper* :  **char -\> bool**

**is\_upper c** is  **true** if and only if  **c** is an ASCII uppercase letter **'A'** to  **'Z'** , that is a byte in the range \[ **0x41** ; **0x5A** \].

*val is\_lower* :  **char -\> bool**

**is\_lower c** is  **true** if and only if  **c** is an ASCII lowercase letter **'a'** to  **'z'** , that is a byte in the range \[ **0x61** ; **0x7A** \].

*val is\_letter* :  **char -\> bool**

**is\_letter c** is  **Char.Ascii.is\_lower** **c \|\|**  **Char.Ascii.is\_upper** **c** .

*val is\_alphanum* :  **char -\> bool**

**is\_alphanum c** is  **Char.Ascii.is\_letter** **c \|\|**  **Char.Ascii.is\_digit** **c** .

*val is\_white* :  **char -\> bool**

**is\_white c** is  **true** if and only if  **c** is an ASCII white space character, that is one of tab  **'\\t'** ( **0x09** ), newline  **'\\n'** ( **0x0A** ), vertical tab ( **0x0B** ), form feed ( **0x0C** ), carriage return  **'\\r'** ( **0x0D** ) or space  **' '** ( **0x20** ),

*val is\_blank* :  **char -\> bool**

**is\_blank c** is  **true** if and only if  **c** is an ASCII blank character, that is either space  **' '** ( **0x20** ) or tab  **'\\t'** ( **0x09** ).

*val is\_graphic* :  **char -\> bool**

**is\_graphic c** is  **true** if and only if  **c** is an ASCII graphic character, that is a byte in the range \[ **0x21** ; **0x7E** \].

*val is\_print* :  **char -\> bool**

**is\_print c** is  **Char.Ascii.is\_graphic** **c \|\| c = ' '** .

*val is\_control* :  **char -\> bool**

**is\_control c** is  **true** if and only if  **c** is an ASCII control character, that is a byte in the range \[ **0x00** ; **0x1F** \] or  **0x7F** .

### Decimal digits

*val is\_digit* :  **char -\> bool**

**is\_digit c** is  **true** if and only if  **c** is an ASCII decimal digit **'0'** to  **'9'** , that is a byte in the range \[ **0x30** ; **0x39** \].

*val digit\_to\_int* :  **char -\> int**

**digit\_to\_int c** is the numerical value of a digit that satisfies  **Char.Ascii.is\_digit** . Raises  **Invalid\_argument** if **Char.Ascii.is\_digit** **c** is  **false** .

*val digit\_of\_int* :  **int -\> char**

**digit\_of\_int n** is an ASCII decimal digit for the decimal value  **abs (n mod 10)** .

### Hexadecimal digits

*val is\_hex\_digit* :  **char -\> bool**

**is\_hex\_digit c** is  **true** if and only if  **c** is an ASCII hexadecimal digit  **'0'** to  **'9'** ,  **'a'** to  **'f'** or  **'A'** to  **'F'** , that is a byte in one of the ranges \[ **0x30** ; **0x39** \], \[ **0x41** ; **0x46** \], \[ **0x61** ; **0x66** \].

*val hex\_digit\_to\_int* :  **char -\> int**

**hex\_digit\_to\_int c** is the numerical value of a digit that satisfies  **Char.Ascii.is\_hex\_digit** . Raises  **Invalid\_argument** if **Char.Ascii.is\_hex\_digit** **c** is  **false** .

*val lower\_hex\_digit\_of\_int* :  **int -\> char**

**lower\_hex\_digit\_of\_int n** is a lowercase ASCII hexadecimal digit for the hexadecimal value  **abs (n mod 16)** .

*val upper\_hex\_digit\_of\_int* :  **int -\> char**

**upper\_hex\_digit\_of\_int n** is an uppercase ASCII hexadecimal digit for the hexadecimal value  **abs (n mod 16)** .

### Casing transforms

*val uppercase* :  **char -\> char**

**uppercase c** is  **c** with ASCII characters  **'a'** to  **'z'** respectively mapped to uppercase characters  **'A'** to  **'Z'** . Other characters are left untouched.

*val lowercase* :  **char -\> char**

**lowercase c** is  **c** with ASCII characters  **'A'** to  **'Z'** respectively mapped to lowercase characters  **'a'** to  **'z'** . Other characters are left untouched.