# Module BatDigest

    module BatDigest: sig .. end

MD5 message digest.

This module provides functions to compute 128-bit ``digests'' of arbitrary-length strings or files. The digests are of cryptographic quality: it is very hard, given a digest, to forge a string having that digest. The algorithm used is MD5.
Author(s): Xavier Leroy (Base module), David Rajchenbach-Teller

    type t = string

The type of digests: 16-character strings.

    val string : string -> t

Return the digest of the given string.

    val substring : string -> int -> int -> t

`Digest.substring s ofs len` returns the digest of the substring of `s` starting at character number `ofs` and containing `len` characters.

    val file : string -> t

Return the digest of the file whose name is given.

    val to_hex : t -> string

Return the printable hexadecimal representation of the given digest.

    val from_hex : string -> t

Convert a hexadecimal representation back into the corresponding digest.
Since 4.00.0
Raises `Invalid_argument` if the argument is not exactly 32 hexadecimal characters.

    val channel : BatIO.input -> int -> Digest.t

If `len` is nonnegative, `Digest.channel ic len` reads `len` characters from channel `ic` and returns their digest, or
Raises `End_of_file` if end-of-file is reached before `len` characters are read. If `len` is negative, `Digest.channel ic len` reads all characters from `ic` until end-of-file is reached and return their digest.

Note This version of `channel` is currently very inefficient if `len` < 0 and requires copying the whole input to a temporary file.

    val output : 'a BatIO.output -> t -> unit

Write a digest on the given output.

    val print : 'a BatIO.output -> Digest.t -> unit

Write a digest on the given output in hexadecimal.

    val input : BatIO.input -> Digest.t

Read a digest from the given input.

    val compare : t -> t -> int

The comparison function for 16-character digest, with the same specification as `Pervasives.compare` and the implementation shared with `String.compare`. Along with the type `t`, this function `compare` allows the module `Digest` to be passed as argument to the functors `Set.Make` and `Map.Make`.
Since 4.00.0