# Module Dbm

    module Dbm: sig .. end

Interface to the NDBM database.

    type t

The type of file descriptors opened on NDBM databases.
`type ``open_flag =`

`|` | `Dbm_rdonly`
`|` | `Dbm_wronly`
`|` | `Dbm_rdwr`
`|` | `Dbm_create` | `(*` | Flags for opening a database (see `Dbm.opendbm`). | `*)`

    exception Dbm_error of string

Raised by the following functions when an error is encountered.

    val opendbm : string -> open_flag list -> int -> t

Open a descriptor on an NDBM database. The first argument is the name of the database (without the `.dir` and `.pag` suffixes). The second argument is a list of flags: `Dbm_rdonly` opens the database for reading only, `Dbm_wronly` for writing only, `Dbm_rdwr` for reading and writing; `Dbm_create` causes the database to be created if it does not already exist. The third argument is the permissions to give to the database files, if the database is created.

    val close : t -> unit

Close the given descriptor.

    val find : t -> string -> string

`find db key` returns the data associated with the given `key` in the database opened for the descriptor `db`. Raise `Not_found` if the `key` has no associated data.

    val add : t -> string -> string -> unit

`add db key data` inserts the pair (`key`, `data`) in the database `db`. If the database already contains data associated with `key`, raise `Dbm_error "Entry already exists"`.

    val replace : t -> string -> string -> unit

`replace db key data` inserts the pair (`key`, `data`) in the database `db`. If the database already contains data associated with `key`, that data is discarded and silently replaced by the new `data`.

    val remove : t -> string -> unit

`remove db key data` removes the data associated with `key` in `db`. If `key` has no associated data, raise `Dbm_error "dbm_delete"`.

    val firstkey : t -> string

See `Dbm.nextkey`.

    val nextkey : t -> string

Enumerate all keys in the given database, in an unspecified order. `firstkey db` returns the first key, and repeated calls to `nextkey db` return the remaining keys. `Not_found` is raised when all keys have been enumerated.

    val iter : (string -> string -> 'a) -> t -> unit

`iter f db` applies `f` to each (`key`, `data`) pair in the database `db`. `f` receives `key` as first argument and `data` as second argument.