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closing tags and attribute quotes, but lets a stock 3.1 install compile the PHP docs. It still compiles with DocBook 3.0, as well. git-svn-id: https://svn.php.net/repository/phpdoc/en/trunk@14693 c90b9560-bf6c-de11-be94-00142212c4b1
254 lines
8.5 KiB
Text
254 lines
8.5 KiB
Text
<reference id="ref.dbm">
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<title>dbm functions</title>
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<titleabbrev>DBM</titleabbrev>
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<partintro>
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<simpara>
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These functions allow you to store records stored in a dbm-style
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database. This type of database (supported by the Berkeley db,
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gdbm, and some system libraries, as well as a built-in flatfile
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library) stores key/value pairs (as opposed to the full-blown
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records supported by relational databases).</simpara>
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<para>
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<example>
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<title>dbm example</title>
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<programlisting role="php">
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$dbm = dbmopen("lastseen", "w");
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if (dbmexists($dbm, $userid)) {
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$last_seen = dbmfetch($dbm, $userid);
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} else {
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dbminsert($dbm, $userid, time());
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}
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do_stuff();
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dbmreplace($dbm, $userid, time());
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dbmclose($dbm);
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</programlisting></example>
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</para>
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</partintro>
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<refentry id="function.dbmopen">
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<refnamediv>
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<refname>dbmopen</refname>
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<refpurpose>opens a dbm database</refpurpose>
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</refnamediv>
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<refsect1>
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<title>Description</title>
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<funcsynopsis>
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<funcdef>int <function>dbmopen</function></funcdef>
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<paramdef>string <parameter>filename</parameter></paramdef>
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<paramdef>string <parameter>flags</parameter></paramdef>
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</funcsynopsis>
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<para>
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The first argument is the full-path filename of the dbm file to be opened
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and the second is the file open mode which is one of "r", "n", "c" or "w"
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for read-only, new (implies read-write, and most likely will truncate an
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already-existing database of the same name), create (implies read-write,
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and will not truncate an already-existing database of the same name)
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and read-write respectively.</para>
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<para>
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Returns an identifer to be passed to the other dbm functions on success,
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or false on failure.</para>
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<para>
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If ndbm support is used, ndbm will actually create filename.dir and
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filename.pag files. gdbm only uses one file, as does the internal flat-file
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support, and Berkeley db creates a filename.db file. Note that PHP does its
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own file locking in addition to any file locking that may be done by the dbm
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library itself. PHP does not delete the .lck files it creates. It uses these
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files simply as fixed inodes on which to do the file locking. For more
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information on dbm files, see your Unix man pages, or obtain GNU's gdbm from
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<filename role="url">ftp://prep.ai.mit.edu/pub/gnu</filename>.</para>
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</refsect1>
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</refentry>
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<refentry id="function.dbmclose">
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<refnamediv>
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<refname>dbmclose</refname>
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<refpurpose>closes a dbm database</refpurpose>
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</refnamediv>
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<refsect1>
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<title>Description</title>
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<funcsynopsis>
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<funcdef>bool <function>dbmclose</function></funcdef>
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<paramdef>int <parameter>dbm_identifier</parameter></paramdef>
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</funcsynopsis>
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<para>
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Unlocks and closes the specified database.</para>
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</refsect1>
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</refentry>
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<refentry id="function.dbmexists">
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<refnamediv>
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<refname>dbmexists</refname>
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<refpurpose>tells if a value exists for a key in a dbm database</refpurpose>
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</refnamediv>
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<refsect1>
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<title>Description</title>
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<funcsynopsis>
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<funcdef>bool <function>dbmexists</function></funcdef>
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<paramdef>int <parameter>dbm_identifier</parameter></paramdef>
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<paramdef>string <parameter>key</parameter></paramdef>
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</funcsynopsis>
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<para>
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Returns true if there is a value associated with the <parameter>key</parameter>.</para>
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</refsect1>
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</refentry>
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<refentry id="function.dbmfetch">
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<refnamediv>
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<refname>dbmfetch</refname>
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<refpurpose>fetches a value for a key from a dbm database</refpurpose>
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</refnamediv>
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<refsect1>
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<title>Description</title>
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<funcsynopsis>
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<funcdef>string <function>dbmfetch</function></funcdef>
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<paramdef>int <parameter>dbm_identifier</parameter></paramdef>
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<paramdef>string <parameter>key</parameter></paramdef>
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</funcsynopsis>
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<para>
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Returns the value associated with <parameter>key</parameter>.</para>
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</refsect1>
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</refentry>
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<refentry id="function.dbminsert">
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<refnamediv>
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<refname>dbminsert</refname>
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<refpurpose>inserts a value for a key in a dbm database</refpurpose>
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</refnamediv>
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<refsect1>
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<title>Description</title>
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<funcsynopsis>
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<funcdef>int <function>dbminsert</function></funcdef>
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<paramdef>int <parameter>dbm_identifier</parameter></paramdef>
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<paramdef>string <parameter>key</parameter></paramdef>
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<paramdef>string <parameter>value</parameter></paramdef>
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</funcsynopsis>
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<para>
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Adds the value to the database with the specified key.</para>
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<para>
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Returns -1 if the database was opened read-only, 0 if the insert
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was successful, and 1 if the specified key already exists. (To replace
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the value, use <function>dbmreplace</function>.)</para>
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</refsect1>
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</refentry>
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<refentry id="function.dbmreplace">
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<refnamediv>
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<refname>dbmreplace</refname>
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<refpurpose>replaces the value for a key in a dbm database</refpurpose>
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</refnamediv>
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<refsect1>
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<title>Description</title>
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<funcsynopsis>
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<funcdef>bool <function>dbmreplace</function></funcdef>
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<paramdef>int <parameter>dbm_identifier</parameter></paramdef>
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<paramdef>string <parameter>key</parameter></paramdef>
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<paramdef>string <parameter>value</parameter></paramdef>
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</funcsynopsis>
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<para>
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Replaces the value for the specified key in the database.</para>
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<para>
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This will also add the key to the database if it didn't already
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exist.</para>
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</refsect1>
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</refentry>
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<refentry id="function.dbmdelete">
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<refnamediv>
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<refname>dbmdelete</refname>
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<refpurpose>deletes the value for a key from a dbm database</refpurpose>
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</refnamediv>
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<refsect1>
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<title>Description</title>
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<funcsynopsis>
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<funcdef>bool <function>dbmdelete</function></funcdef>
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<paramdef>int <parameter>dbm_identifier</parameter></paramdef>
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<paramdef>string <parameter>key</parameter></paramdef>
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</funcsynopsis>
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<para>
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Deletes the value for <parameter>key</parameter> in the database.</para>
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<para>
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Returns false if the key didn't exist in the database.</para>
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</refsect1>
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</refentry>
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<refentry id="function.dbmfirstkey">
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<refnamediv>
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<refname>dbmfirstkey</refname>
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<refpurpose>retrieves the first key from a dbm database</refpurpose>
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</refnamediv>
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<refsect1>
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<title>Description</title>
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<funcsynopsis>
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<funcdef>string <function>dbmfirstkey</function></funcdef>
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<paramdef>int <parameter>dbm_identifier</parameter></paramdef>
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</funcsynopsis>
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<para>
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Returns the first key in the database. Note that no particular order
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is guaranteed since the database may be built using a hash-table,
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which doesn't guarantee any ordering.</para>
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</refsect1>
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</refentry>
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<refentry id="function.dbmnextkey">
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<refnamediv>
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<refname>dbmnextkey</refname>
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<refpurpose>retrieves the next key from a dbm database</refpurpose>
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</refnamediv>
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<refsect1>
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<title>Description</title>
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<funcsynopsis>
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<funcdef>string <function>dbmnextkey</function></funcdef>
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<paramdef>int <parameter>dbm_identifier</parameter></paramdef>
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<paramdef>string <parameter>key</parameter></paramdef>
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</funcsynopsis>
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<para>
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Returns the next key after <parameter>key</parameter>. By calling
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<function>dbmfirstkey</function> followed by successive
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calls to <function>dbmnextkey</function> it is possible to
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visit every key/value pair in the dbm database. For example:
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<example>
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<title>Visiting every key/value pair in a dbm database.</title>
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<programlisting>
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$key = dbmfirstkey($dbm_id);
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while ($key) {
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echo "$key = " . dbmfetch($dbm_id, $key) . "\n";
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$key = dbmnextkey($dbm_id, $key);
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}
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</programlisting>
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</example></para>
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</refsect1>
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</refentry>
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<refentry id="function.dblist">
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<refnamediv>
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<refname>dblist</refname>
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<refpurpose>describes the dbm-compatible library being used</refpurpose>
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</refnamediv>
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<refsect1>
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<title>Description</title>
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<funcsynopsis>
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<funcdef>string <function>dblist</function></funcdef>
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<paramdef>void</paramdef>
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</funcsynopsis>
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</refsect1>
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</refentry>
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</reference>
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<!-- Keep this comment at the end of the file
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Local variables:
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mode: sgml
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sgml-omittag:t
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sgml-shorttag:t
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sgml-minimize-attributes:nil
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sgml-always-quote-attributes:t
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sgml-indent-step:1
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sgml-indent-data:t
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sgml-parent-document:nil
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sgml-default-dtd-file:"../manual.ced"
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sgml-exposed-tags:nil
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sgml-local-catalogs:nil
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sgml-local-ecat-files:nil
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End:
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-->
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