### DB->err

`

###

    #include <db.h>

    void
    DB->err(DB *db, int error, const char *fmt, ...);

    void
    DB->errx(DB *db, const char *fmt, ...);

### Description: DB->err

The DB_ENV->err, DB_ENV->errx, DB->err and DB->errx methods provide error-messaging functionality for applications written using the Berkeley DB library.

The DB->err and DB_ENV->err methods constructs an error message consisting of the following elements:

> An optional prefix string
>   If no error callback function has been set using the DB_ENV->set_errcall method, any prefix string specified using the DB_ENV->set_errpfx method, followed by two separating characters: a colon and a <space> character.
> An optional printf-style message
>   The supplied message fmt, if non-NULL, in which the ANSI C X3.159-1989 (ANSI C) printf function specifies how subsequent parameters are converted for output.
> A separator
>   Two separating characters: a colon and a <space> character.
> A standard error string
>   The standard system or Berkeley DB library error string associated with the error value, as returned by the db_strerror method.

The DB->errx and DB_ENV->errx methods are the same as the DB->err and DB_ENV->err methods, except they do not append the final separator characters and standard error string to the error message.

This constructed error message is then handled as follows:

> If an error callback function has been set (see DB->set_errcall and DB_ENV->set_errcall), that function is called with two parameters: any prefix string specified (see DB->set_errpfx and DB_ENV->set_errpfx) and the error message.

> If a C library FILE * has been set (see DB->set_errfile and DB_ENV->set_errfile), the error message is written to that output stream.

> If none of these output options has been configured, the error message is written to stderr, the standard error output stream.

### Parameters

error
  The error parameter is the error value for which the DB_ENV->err and DB->err methods will display a explanatory string.
fmt
  The fmt parameter is an optional printf-style message to display.

### Class

DB

### See Also

Databases and Related Methods`

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