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

# Stdlib.Uchar(3o)

no description

## NAME

Stdlib.Uchar - no description

## Module

Module   Stdlib.Uchar

## Documentation

Module **Uchar**\
  :  **(module Stdlib\_\_Uchar)**

*type t*

The type for Unicode characters.

A value of this type represents a Unicode scalar value which is an integer in the ranges  **0x0000** ... **0xD7FF** or **0xE000** ... **0x10FFFF** .

*val min* :  **t**

**min** is U+0000.

*val max* :  **t**

**max** is U+10FFFF.

*val bom* :  **t**

**bom** is U+FEFF, the byte order mark (BOM) character.

**Since** 4.06

*val rep* :  **t**

**rep** is U+FFFD, the replacement character.

**Since** 4.06

*val succ* :  **t -\> t**

**succ u** is the scalar value after  **u** in the set of Unicode scalar values.

**Raises Invalid\_argument** if  **u** is  **Uchar.max** .

*val pred* :  **t -\> t**

**pred u** is the scalar value before  **u** in the set of Unicode scalar values.

**Raises Invalid\_argument** if  **u** is  **Uchar.min** .

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

**is\_valid n** is  **true** if and only if  **n** is a Unicode scalar value (i.e. in the ranges  **0x0000** ... **0xD7FF** or  **0xE000** ... **0x10FFFF** ).

*val of\_int* :  **int -\> t**

**of\_int i** is  **i** as a Unicode character.

**Raises Invalid\_argument** if  **i** does not satisfy  **Uchar.is\_valid** .

*val to\_int* :  **t -\> int**

**to\_int u** is  **u** as an integer.

*val is\_char* :  **t -\> bool**

**is\_char u** is  **true** if and only if  **u** is a latin1 OCaml character.

*val of\_char* :  **char -\> t**

**of\_char c** is  **c** as a Unicode character.

*val to\_char* :  **t -\> char**

**to\_char u** is  **u** as an OCaml latin1 character.

**Raises Invalid\_argument** if  **u** does not satisfy  **Uchar.is\_char** .

*val equal* :  **t -\> t -\> bool**

**equal u u'** is  **u = u'** .

*val compare* :  **t -\> t -\> int**

**compare u u'** is  **Stdlib.compare u u'** .

*val seeded\_hash* :  **int -\> t -\> int**

**seeded\_hash seed u** A seeded hash function with the same output value as **Hashtbl.seeded\_hash** . This function allows this module to be passed as an argument to the functor  **Hashtbl.MakeSeeded** .

**Since** 5.3

*val hash* :  **t -\> int**

An unseeded hash function with the same output value as  **Hashtbl.hash** . This function allows this module to be passed as an argument to the functor **Hashtbl.Make** .

**Before5.3** The hashing algorithm was different. Use  **Hashtbl.rebuild** for stored tables which used this hashing function

### UTF codecs tools

*type utf\_decode*

The type for UTF decode results. Values of this type represent the result of a Unicode Transformation Format decoding attempt.

*val utf\_decode\_is\_valid* :  **utf\_decode -\> bool**

**utf\_decode\_is\_valid d** is  **true** if and only if  **d** holds a valid decode.

*val utf\_decode\_uchar* :  **utf\_decode -\> t**

**utf\_decode\_uchar d** is the Unicode character decoded by  **d** if **utf\_decode\_is\_valid d** is  **true** and  **Uchar.rep** otherwise.

*val utf\_decode\_length* :  **utf\_decode -\> int**

**utf\_decode\_length d** is the number of elements from the source that were consumed by the decode  **d** . This is always strictly positive and smaller or equal to  **4** . The kind of source elements depends on the actual decoder; for the decoders of the standard library this function always returns a length in bytes.

*val utf\_decode* :  **int -\> t -\> utf\_decode**

**utf\_decode n u** is a valid UTF decode for  **u** that consumed  **n** elements from the source for decoding.  **n** must be positive and smaller or equal to  **4** (this is not checked by the module).

*val utf\_decode\_invalid* :  **int -\> utf\_decode**

**utf\_decode\_invalid n** is an invalid UTF decode that consumed  **n** elements from the source to error.  **n** must be positive and smaller or equal to  **4** (this is not checked by the module). The resulting decode has  **Uchar.rep** as the decoded Unicode character.

*val utf\_8\_decode\_length\_of\_byte* :  **char -\> int**

**utf\_8\_decode\_length\_of\_byte byte** is the number of bytes, from 1 to  **Uchar.max\_utf\_8\_decode\_length** , that a valid UTF-8 decode starting with byte  **byte** would consume or  **0** if  **byte** cannot start a valid decode.

**Since** 5.4

*val max\_utf\_8\_decode\_length* :  **int**

**max\_utf\_8\_decode\_length** is  **4** , the maximal number of bytes a valid or invalid UTF-8 decode can consume.

**Since** 5.4

*val utf\_8\_byte\_length* :  **t -\> int**

**utf\_8\_byte\_length u** is the number of bytes needed to encode **u** in UTF-8.

*val utf\_16\_byte\_length* :  **t -\> int**

**utf\_16\_byte\_length u** is the number of bytes needed to encode **u** in UTF-16.