# Db::err

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    #include <db_cxx.h>

    Db::err(int error, const char *fmt, ...);

    Db::errx(const char *fmt, ...);

# Description

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

The DbEnv::err method constructs an error message consisting of the following elements:

> An optional prefix string
>   If no error callback method has been set using the DbEnv::set_errcall method, any prefix string specified using the DbEnv::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 arguments 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 DbEnv::strerror method.

This constructed error message is then handled as follows:

> If an error callback method has been set (see Db::set_errcall and DbEnv::set_errcall), that method is called with two arguments: any prefix string specified (see Db::set_errpfx and DbEnv::set_errpfx) and the error message.

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

> If a C++ ostream has been set (see DbEnv::set_error_stream and Db::set_error_stream), the error message is written to that stream.

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

The DbEnv::errx and Db::errx methods perform identically to the DbEnv::err and Db::err methods, except that they do not append the final separator characters and standard error string to the error message.

# Class

Db

# See Also

Databases and Related Methods`

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