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Db::set_errcall
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#include &lt;db_cxx.h&gt;

void Db::set_errcall(void (*db_errcall_fcn)
 (const DbEnv *dbenv, const char *errpfx, const char *msg));
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Description: Db::set_errcall
When an error occurs in the Berkeley DB library, an exception is thrown or an
error return value is returned by the interface. In some cases,
however, the errno value may be insufficient to completely
describe the cause of the error, especially during initial application
debugging.
The <a href="../../db4-devel-4.7.25/api_cxx/env_set_errcall.html">DbEnv::set_errcall</a> 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. It is up to
the db_errcall_fcn function to display the error message in an
appropriate manner.
Setting db_errcall_fcn to NULL unconfigures the callback interface.
Alternatively, you can use the <a href="../../db4-devel-4.7.25/api_cxx/env_set_error_stream.html">DbEnv::set_error_stream</a> and
<a href="../../db4-devel-4.7.25/api_cxx/db_set_error_stream.html">Db::set_error_stream</a> methods to display the additional information via
an output stream, or the <a href="../../db4-devel-4.7.25/api_cxx/db_set_errfile.html">Db::set_errfile</a> or
<a href="../../db4-devel-4.7.25/api_cxx/env_set_errfile.html">DbEnv::set_errfile</a> 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.
For <a href="../../db4-devel-4.7.25/api_cxx/db_class.html">Db</a> handles opened inside of Berkeley DB environments, calling the
Db::set_errcall method affects the entire environment and is equivalent to calling
the <a href="../../db4-devel-4.7.25/api_cxx/env_set_errcall.html">DbEnv::set_errcall</a> method.
The Db::set_errcall method configures operations performed using the specified
<a href="../../db4-devel-4.7.25/api_cxx/db_class.html">Db</a> handle, not all operations performed on the underlying
database.
The Db::set_errcall method may be called at any time during the life of the
application.
Parameters 
 db_errcall_fcn<ul compact><li>The db_errcall_fcn parameter is the application-specified error
reporting function. The function takes three parameters:
 
dbenv<ul compact><li>The dbenv parameter is the enclosing database environment.</ul>
errpfx<ul compact><li>The errpfx parameter is the prefix string (as previously set by
<a href="../../db4-devel-4.7.25/api_cxx/db_set_errpfx.html">Db::set_errpfx</a> or <a href="../../db4-devel-4.7.25/api_cxx/env_set_errpfx.html">DbEnv::set_errpfx</a>).</ul>
msg<ul compact><li>The msg parameter is the error message string.</ul>
 
Berkeley DB is not re-entrant. Callback functions should not attempt to make
library calls (for example, to release locks or close open handles).
Re-entering Berkeley DB is not guaranteed to work correctly, and the results
are undefined.</ul>
 
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 Class
<a href="../../db4-devel-4.7.25/api_cxx/db_class.html">Db</a>
 See Also
<a href="../../db4-devel-4.7.25/api_cxx/db_list.html">Databases and Related Methods</a>
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