# DbEnv::set_errcall

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    #include <db_cxx.h>

    void DbEnv::set_errcall(
        void (*db_errcall_fcn)(const char *errpfx, char *msg));

# Description

When an error occurs in the Berkeley DB library, an exception is thrown or an error return value is returned by the method. In some cases, however, the errno value may be insufficient to completely describe the cause of the error, especially during initial application debugging.

The DbEnv::set_errcall and Db::set_errcall methods are used to enhance the mechanism for reporting error messages to the application. In some cases, when an error occurs, Berkeley DB will call db_errcall_fcn with additional error information. The function must be defined with two arguments; the first will be the prefix string (as previously set by Db::set_errpfx or DbEnv::set_errpfx); the second will be the error message string. It is up to the db_errcall_fcn method to display the error message in an appropriate manner.

Alternatively, you can use the DbEnv::set_error_stream method to display the additional information via an output stream, or the Db::set_errfile or DbEnv::set_errfile methods to display the additional information via a C library FILE *. You should not mix these approaches.

This error-logging enhancement does not slow performance or significantly increase application size, and may be run during normal operation as well as during application debugging.

The DbEnv::set_errcall interface may be used to configure Berkeley DB at any time during the life of the application.

# Class

DbEnv

# See Also

DbEnv::close, DbEnv::err, DbEnv::errx DbEnv::open, DbEnv::remove, DbEnv::set_alloc, DbEnv::set_cachesize, DbEnv::set_data_dir, DbEnv::set_errcall, DbEnv::set_errfile, DbEnv::set_error_stream, DbEnv::set_errpfx, DbEnv::set_feedback, DbEnv::set_flags, DbEnv::set_paniccall, DbEnv::set_recovery_init, DbEnv::set_rpc_server, DbEnv::set_shm_key, DbEnv::set_tas_spins, DbEnv::set_tmp_dir, DbEnv::set_timeout, DbEnv::set_verbose, DbEnv::strerror and DbEnv::version.`

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