1<?xml version="1.0" encoding="UTF-8" standalone="no"?> 2<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> 3<html xmlns="http://www.w3.org/1999/xhtml"> 4 <head> 5 <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /> 6 <title>Dbc::count()</title> 7 <link rel="stylesheet" href="apiReference.css" type="text/css" /> 8 <meta name="generator" content="DocBook XSL Stylesheets V1.73.2" /> 9 <link rel="start" href="index.html" title="Berkeley DB C++ API Reference" /> 10 <link rel="up" href="dbc.html" title="Chapter 3. The Dbc Handle" /> 11 <link rel="prev" href="dbccmp.html" title="Dbc::cmp()" /> 12 <link rel="next" href="dbcdel.html" title="Dbc::del()" /> 13 </head> 14 <body> 15 <div class="navheader"> 16 <table width="100%" summary="Navigation header"> 17 <tr> 18 <th colspan="3" align="center">Dbc::count()</th> 19 </tr> 20 <tr> 21 <td width="20%" align="left"><a accesskey="p" href="dbccmp.html">Prev</a> </td> 22 <th width="60%" align="center">Chapter 3. 23 The Dbc Handle 24 </th> 25 <td width="20%" align="right"> <a accesskey="n" href="dbcdel.html">Next</a></td> 26 </tr> 27 </table> 28 <hr /> 29 </div> 30 <div class="sect1" lang="en" xml:lang="en"> 31 <div class="titlepage"> 32 <div> 33 <div> 34 <h2 class="title" style="clear: both"><a id="dbccount"></a>Dbc::count()</h2> 35 </div> 36 </div> 37 </div> 38 <pre class="programlisting">#include <db_cxx.h> 39 40int 41Dbc::count(db_recno_t *countp, u_int32_t flags);</pre> 42 <p> 43 The <code class="methodname">Dbc::count()</code> method returns a count of the number of data 44 items for the key to which the cursor refers. 45 </p> 46 <p> 47 The <code class="methodname">Dbc::count()</code> <span> 48 49 <span> 50 method either returns a non-zero error value or throws an 51 exception that encapsulates a non-zero error value on 52 failure, and returns 0 on success. 53 </span> 54 </span> 55 </p> 56 <div class="sect2" lang="en" xml:lang="en"> 57 <div class="titlepage"> 58 <div> 59 <div> 60 <h3 class="title"><a id="id1655201"></a>Parameters</h3> 61 </div> 62 </div> 63 </div> 64 <div class="sect3" lang="en" xml:lang="en"> 65 <div class="titlepage"> 66 <div> 67 <div> 68 <h4 class="title"><a id="id1655322"></a>countp</h4> 69 </div> 70 </div> 71 </div> 72 <p> 73 The <span class="bold"><strong>countp</strong></span> parameter references 74 memory into which the count of the number of duplicate data items is 75 copied. 76 </p> 77 </div> 78 <div class="sect3" lang="en" xml:lang="en"> 79 <div class="titlepage"> 80 <div> 81 <div> 82 <h4 class="title"><a id="id1655325"></a>flags</h4> 83 </div> 84 </div> 85 </div> 86 <p> 87 The <span class="bold"><strong>flags</strong></span> parameter is currently 88 unused, and must be set to 0. 89 </p> 90 </div> 91 </div> 92 <div class="sect2" lang="en" xml:lang="en"> 93 <div class="titlepage"> 94 <div> 95 <div> 96 <h3 class="title"><a id="id1655461"></a>Errors</h3> 97 </div> 98 </div> 99 </div> 100 <p> 101 The <code class="methodname">Dbc::count()</code> <span> 102 103 <span> 104 method may fail and throw a <a class="link" href="dbexception.html" title="Chapter 6. The DbException Class">DbException</a> 105 exception, encapsulating one of the following non-zero errors, or return one 106 of the following non-zero errors: 107 </span> 108 </span> 109 </p> 110 <div class="sect3" lang="en" xml:lang="en"> 111 <div class="titlepage"> 112 <div> 113 <div> 114 <h4 class="title"><a id="id1655445"></a><span>DbRepHandleDeadException or</span> DB_REP_HANDLE_DEAD</h4> 115 </div> 116 </div> 117 </div> 118 <p> 119 When a client synchronizes with the master, it is possible for committed 120 transactions to be rolled back. This invalidates all the database and cursor 121 handles opened in the replication environment. Once this occurs, an attempt to use 122 such a handle will 123 <span> 124 throw a <a class="xref" href="dbrephandledead.html" title="DbRepHandleDeadException">DbRepHandleDeadException</a> (if 125 your application is configured to throw exceptions), or 126 </span> 127 return <code class="literal">DB_REP_HANDLE_DEAD</code>. 128 The application will need to discard the handle and open a new one in order to 129 continue processing. 130 </p> 131 </div> 132 <div class="sect3" lang="en" xml:lang="en"> 133 <div class="titlepage"> 134 <div> 135 <div> 136 <h4 class="title"><a id="id1655523"></a><span>DbDeadlockException or </span>DB_REP_LOCKOUT</h4> 137 </div> 138 </div> 139 </div> 140 <p> 141 The operation was blocked by client/master synchronization. 142 </p> 143 <p> 144 <a class="xref" href="dbdeadlock.html" title="DbDeadlockException">DbDeadlockException</a> is thrown if 145 your Berkeley DB API is configured to throw exceptions. 146 Otherwise, <code class="literal">DB_REP_LOCKOUT</code> is returned. 147 </p> 148 </div> 149 <div class="sect3" lang="en" xml:lang="en"> 150 <div class="titlepage"> 151 <div> 152 <div> 153 <h4 class="title"><a id="id1655556"></a>EINVAL</h4> 154 </div> 155 </div> 156 </div> 157 <p> 158 If the cursor has not been initialized; or if an invalid flag value or parameter was specified. 159 </p> 160 </div> 161 </div> 162 <div class="sect2" lang="en" xml:lang="en"> 163 <div class="titlepage"> 164 <div> 165 <div> 166 <h3 class="title"><a id="id1655530"></a>Class</h3> 167 </div> 168 </div> 169 </div> 170 <p> 171 <a class="link" href="dbc.html" title="Chapter 3. The Dbc Handle">Dbc</a> 172 </p> 173 </div> 174 <div class="sect2" lang="en" xml:lang="en"> 175 <div class="titlepage"> 176 <div> 177 <div> 178 <h3 class="title"><a id="id1655294"></a>See Also</h3> 179 </div> 180 </div> 181 </div> 182 <p> 183 <a class="xref" href="dbc.html#dbclist" title="Database Cursors and Related Methods">Database Cursors and Related Methods</a> 184 </p> 185 </div> 186 </div> 187 <div class="navfooter"> 188 <hr /> 189 <table width="100%" summary="Navigation footer"> 190 <tr> 191 <td width="40%" align="left"><a accesskey="p" href="dbccmp.html">Prev</a> </td> 192 <td width="20%" align="center"> 193 <a accesskey="u" href="dbc.html">Up</a> 194 </td> 195 <td width="40%" align="right"> <a accesskey="n" href="dbcdel.html">Next</a></td> 196 </tr> 197 <tr> 198 <td width="40%" align="left" valign="top">Dbc::cmp() </td> 199 <td width="20%" align="center"> 200 <a accesskey="h" href="index.html">Home</a> 201 </td> 202 <td width="40%" align="right" valign="top"> Dbc::del()</td> 203 </tr> 204 </table> 205 </div> 206 </body> 207</html> 208