| Current Path : /proc/2/cwd/usr/share/doc/db4-devel-4.7.25/ref/am_misc/ |
| Current File : //proc/2/cwd/usr/share/doc/db4-devel-4.7.25/ref/am_misc/error.html |
<!--$Id: error.so,v 10.22 2003/10/18 19:15:56 bostic Exp $-->
<!--Copyright (c) 1997,2008 Oracle. All rights reserved.-->
<!--See the file LICENSE for redistribution information.-->
<html>
<head>
<title>Berkeley DB Reference Guide: Error support</title>
<meta name="description" content="Berkeley DB: An embedded database programmatic toolkit.">
<meta name="keywords" content="embedded,database,programmatic,toolkit,btree,hash,hashing,transaction,transactions,locking,logging,access method,access methods,Java,C,C++">
</head>
<body bgcolor=white>
<a name="2"><!--meow--></a>
<table width="100%"><tr valign=top>
<td><b><dl><dt>Berkeley DB Reference Guide:<dd>Access Methods</dl></b></td>
<td align=right><a href="../am_misc/perm.html"><img src="../../images/prev.gif" alt="Prev"></a><a href="../toc.html"><img src="../../images/ref.gif" alt="Ref"></a><a href="../am_misc/stability.html"><img src="../../images/next.gif" alt="Next"></a>
</td></tr></table>
<p align=center><b>Error support</b></p>
<p>Berkeley DB offers programmatic support for displaying error return values.</p>
<p>The <a href="../../api_c/env_strerror.html">db_strerror</a> function returns a pointer to the error
message corresponding to any Berkeley DB error return, similar to the ANSI C
strerror function, but is able to handle both system error returns and
Berkeley DB specific return values.</p>
<p>For example:</p>
<blockquote><pre>int ret;
if ((ret = dbp->put(dbp, NULL, &key, &data, 0)) != 0) {
fprintf(stderr, "put failed: %s\n", db_strerror(ret));
return (1);
}</pre></blockquote>
<p>There are also two additional error methods, <a href="../../api_c/db_err.html">DB->err</a> and
<a href="../../api_c/db_err.html">DB->errx</a>. These methods work like the ANSI C X3.159-1989 (ANSI C) printf
function, taking a printf-style format string and argument list, and
writing a message constructed from the format string and arguments.</p>
<p>The <a href="../../api_c/db_err.html">DB->err</a> method appends the standard error string to the
constructed message; the <a href="../../api_c/db_err.html">DB->errx</a> method does not. These methods
provide simpler ways of displaying Berkeley DB error messages. For example,
if your application tracks session IDs in a variable called session_id,
it can include that information in its error messages:</p>
<p>Error messages can additionally be configured to always include a prefix
(for example, the program name) using the <a href="../../api_c/db_set_errpfx.html">DB->set_errpfx</a> method.</p>
<blockquote><pre>#define DATABASE "access.db"
<p>
int ret;
<p>
(void)dbp->set_errpfx(dbp, program_name);
<p>
if ((ret = dbp->open(dbp,
NULL, DATABASE, NULL, DB_BTREE, DB_CREATE, 0664)) != 0) {
dbp->err(dbp, ret, "%s", DATABASE);
dbp->errx(dbp,
"contact your system administrator: session ID was %d",
session_id);
return (1);
}</pre></blockquote>
<p>For example, if the program were called my_app and the open call returned
an EACCESS system error, the error messages shown would appear as follows:</p>
<blockquote><pre>my_app: access.db: Permission denied.
my_app: contact your system administrator: session ID was 14</pre></blockquote>
<table width="100%"><tr><td><br></td><td align=right><a href="../am_misc/perm.html"><img src="../../images/prev.gif" alt="Prev"></a><a href="../toc.html"><img src="../../images/ref.gif" alt="Ref"></a><a href="../am_misc/stability.html"><img src="../../images/next.gif" alt="Next"></a>
</td></tr></table>
<p><font size=1>Copyright (c) 1996,2008 Oracle. All rights reserved.</font>
</body>
</html>
Copyright 2K16 - 2K18 Indonesian Hacker Rulez
;?>)