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git-svn-id: https://svn.php.net/repository/phpdoc/en/trunk@10098 c90b9560-bf6c-de11-be94-00142212c4b1
909 lines
28 KiB
Text
909 lines
28 KiB
Text
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<reference id="ref.array">
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<title>Array functions</title>
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<titleabbrev>Arrays</titleabbrev>
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<refentry id="function.array">
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<refnamediv>
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<refname>array</refname>
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<refpurpose>
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Create an array
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</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>array <function>array</function></funcdef>
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<varargs>
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</funcsynopsis>
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<para>
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Returns an array of the parameters. The parameters can be given
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an index with the <literal>=></literal> operator.
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<note>
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<para>
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<function>array</function> is a language construct used to represent
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literal arrays, and not a regular function.
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</para>
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</note>
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<para>
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The following example demonstrates how to create a
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two-dimensional array, how to specify keys for associative
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arrays, and how to skip-and-continue numeric indices in normal
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arrays.
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<example>
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<title><function>array</function> example</title>
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<programlisting>
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$fruits = array(
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"fruits" => array("a"=>"orange","b"=>"banana","c"=>"apple"),
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"numbers" => array(1, 2, 3, 4, 5, 6),
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"holes" => array("first", 5 => "second", "third")
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);
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</programlisting></example>
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<para>
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See also:
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<function>list</function>.
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</refsect1>
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</refentry>
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<refentry id="function.array-walk">
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<refnamediv>
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<refname>array_walk</refname>
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<refpurpose>
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Apply a user function to every member of an array.
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</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>array_walk</function></funcdef>
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<paramdef>array <parameter>arr</parameter></paramdef>
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<paramdef>string <parameter>func</parameter></paramdef>
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</funcsynopsis>
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<simpara>
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Applies the function named by <parameter>func</parameter> to each
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element of <parameter>arr</parameter>. The elements are passed as
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the first argument of <parameter>func</parameter>; if
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<parameter>func</parameter> requires more than one argument, a
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warning will be generated each time
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<function>array_walk</function> calls
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<parameter>func</parameter>. These warnings may be suppressed by
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prepending the '@' sign to the <function>array_walk</function>
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call, or by using <function>error_reporting</function>.
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<note>
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<para>
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<parameter>func</parameter> will actually be working with the
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elements of <parameter>arr</parameter>, so any changes made to
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those elements will be made in the array itself.
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</para>
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</note>
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<para>
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<example>
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<title><function>array_walk</function> example</title>
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<programlisting>
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$fruits = array("d"=>"lemon","a"=>"orange","b"=>"banana","c"=>"apple");
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function test_alter( $item1 ) {
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$item1 = 'bogus';
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}
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function test_print( $item2 ) {
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echo "$item2<br>\n";
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}
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array_walk( $fruits, 'test_print' );
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array_walk( $fruits, 'test_alter' );
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array_walk( $fruits, 'test_print' );
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</programlisting>
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</example>
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<simpara>
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See also <function>each</function> and <function>list</function>.
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</refsect1>
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</refentry>
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<refentry id="function.arsort">
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<refnamediv>
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<refname>arsort</refname>
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<refpurpose>
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Sort an array in reverse order and maintain index association
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</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>void <function>arsort</function></funcdef>
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<paramdef>array <parameter>array</parameter></paramdef>
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</funcsynopsis>
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<para>
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This function sorts an array such that array indices maintain their
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correlation with the array elements they are associated with. This is
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used mainly when sorting associative arrays where the actual element
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order is significant.
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<example>
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<title><function>arsort</function> example</title>
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<programlisting>
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$fruits = array("d"=>"lemon","a"=>"orange","b"=>"banana","c"=>"apple");
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arsort($fruits);
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for(reset($fruits); $key = key($fruits); next($fruits)) {
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echo "fruits[$key] = ".$fruits[$key]."\n";
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}
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</programlisting></example>
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This example would display:
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<computeroutput>
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fruits[a] = orange
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fruits[d] = lemon
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fruits[b] = banana
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fruits[c] = apple
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</computeroutput>
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The fruits have been sorted in reverse alphabetical order, and
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the index associated with each element has been maintained.
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<para>
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See also: <function>asort</function>, <function>rsort</function>,
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<function>ksort</function>, and <function>sort</function>.
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</refsect1>
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</refentry>
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<refentry id="function.asort">
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<refnamediv>
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<refname>asort</refname>
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<refpurpose>Sort an array and maintain index association</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>void <function>asort</function></funcdef>
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<paramdef>array <parameter>array</parameter></paramdef>
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</funcsynopsis>
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<para>
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This function sorts an array such that array indices maintain their
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correlation with the array elements they are associated with. This is
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used mainly when sorting associative arrays where the actual element
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order is significant.
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<example>
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<title><function>asort</function> example</title>
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<programlisting>
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$fruits = array("d"=>"lemon","a"=>"orange","b"=>"banana","c"=>"apple");
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asort($fruits);
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for(reset($fruits); $key = key($fruits); next($fruits)) {
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echo "fruits[$key] = ".$fruits[$key]."\n";
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}
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</programlisting></example>
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This example would display:
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<computeroutput>
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fruits[c] = apple
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fruits[b] = banana
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fruits[d] = lemon
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fruits[a] = orange
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</computeroutput>
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The fruits have been sorted in alphabetical order, and the index
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associated with each element has been maintained.
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<para>
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See also <function>arsort</function>, <function>rsort</function>,
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<function>ksort</function>, and <function>sort</function>.
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</refsect1>
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</refentry>
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<refentry id="function.count">
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<refnamediv>
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<refname>count</refname>
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<refpurpose>count elements in a variable</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>count</function></funcdef>
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<paramdef>mixed <parameter>var</parameter></paramdef>
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</funcsynopsis>
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<para>
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Returns the number of elements in <parameter>var</parameter>, which is
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typically an array (since anything else will have one element).
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<para>
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Returns 1 if the variable is not an array.
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<para>
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Returns 0 if the variable is not set.
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<warning>
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<para>
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<function>count</function> may return 0 for a variable that isn't
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set, but it may also return 0 for a variable that has been initialized
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with an empty array. Use <function>isset</function> to test if a
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variable is set.
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</para>
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</warning>
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<para>
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See also:
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<function>sizeof</function>, <function>isset</function>, and
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<function>is_array</function>.
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</refsect1>
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</refentry>
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<refentry id="function.current">
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<refnamediv>
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<refname>current</refname>
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<refpurpose>Return the current element in an array</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>mixed <function>current</function></funcdef>
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<paramdef>array <parameter>array</parameter></paramdef>
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</funcsynopsis>
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<para>
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Every array has an internal pointer to its "current" element,
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which is initialized to the first element inserted into the
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array.
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<para>
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The <function>current</function> function simply returns the
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array element that's currently being pointed by the internal
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pointer. It does not move the pointer in any way. If the
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internal pointer points beyond the end of the elements list,
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<function>current</function> returns false.
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<warning>
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<para>
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If the array contains empty elements (0 or "", the empty string)
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then this function will return false for these elements as well.
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This makes it impossible to determine if you are really at the
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end of the list in such an array using <function>current</function>.
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To properly traverse an array that may contain empty elements,
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use the <function>each</function> function.
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</warning>
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<para>
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See also:
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<function>end</function>, <function>next</function>,
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<function>prev</function> and <function>reset</function>.
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</refsect1>
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</refentry>
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<refentry id="function.each">
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<refnamediv>
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<refname>each</refname>
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<refpurpose>Return the next key and value pair from an array</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>array <function>each</function></funcdef>
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<paramdef>array <parameter>array</parameter></paramdef>
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</funcsynopsis>
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<para>
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Returns the current key and value pair from the array
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<parameter>array</parameter> and advances the array
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cursor. This pair is returned in a four-element array,
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with the keys <emphasis>0</emphasis>, <emphasis>1</emphasis>,
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<emphasis>key</emphasis>, and <emphasis>value</emphasis>. Elements
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<emphasis>0</emphasis> and <emphasis>key</emphasis> contain
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the key name of the array element, and <emphasis>1</emphasis>
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and <emphasis>value</emphasis> contain the data.
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<para>
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If the internal pointer for the array points past the end of the
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array contents, <function>each</function> returns false.
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<para>
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<example>
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<title><function>each</function> examples</title>
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<programlisting>
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$foo = array( "bob", "fred", "jussi", "jouni" );
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$bar = each( $foo );
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</programlisting>
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<para>
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<literal>$bar</literal> now contains the following key/value
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pairs:
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<itemizedlist spacing="compact">
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<listitem><simpara>0 => 0
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<listitem><simpara>1 => 'bob'
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<listitem><simpara>key => 0
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<listitem><simpara>value => 'bob'
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</itemizedlist>
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<programlisting>
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$foo = array( "Robert" => "Bob", "Seppo" => "Sepi" );
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$bar = each( $foo );
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</programlisting>
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<para>
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<literal>$bar</literal> now contains the following key/value
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pairs:
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<itemizedlist spacing="compact">
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<listitem><simpara>0 => 'Robert'
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<listitem><simpara>1 => 'Bob'
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<listitem><simpara>key => 'Robert'
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<listitem><simpara>value => 'Bob'
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</itemizedlist>
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</example>
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<para>
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<function>each</function> is typically used in conjunction with
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<function>list</function> to traverse an array; for instance,
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$HTTP_POST_VARS:
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<example><title>Traversing $HTTP_POST_VARS with <function>each</function></title>
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<programlisting>
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echo "Values submitted via POST method:<br>";
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while (list($key, $val) = each($HTTP_POST_VARS)) {
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echo "$key => $val<br>";
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}
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</programlisting>
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</example>
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<para>
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After <function>each</function> has executed, the array cursor
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will be left on the next element of the array, or on the last
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element if it hits the end of the array.
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<para>
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See also <function>key</function>, <function>list</function>,
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<function>current</function>, <function>reset</function>,
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<function>next</function>, and <function>prev</function>.
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</refsect1>
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</refentry>
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<refentry id="function.end">
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<refnamediv>
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<refname>end</refname>
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<refpurpose>Set the internal pointer of an array to its last element</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><function>end</function></funcdef>
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<paramdef>array <parameter>array</parameter></paramdef>
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</funcsynopsis>
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<para>
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<function>end</function> advances <parameter>array</parameter>'s
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internal pointer to the last element.
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<para>
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See also:
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<function>current</function>, <function>each</function>, <function>end</function>
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<function>next</function> and <function>reset</function>
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</refsect1>
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</refentry>
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<refentry id="function.key">
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<refnamediv>
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<refname>key</refname>
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<refpurpose>Fetch a key from an associative array</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>mixed <function>key</function></funcdef>
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<paramdef>array <parameter>array</parameter></paramdef>
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</funcsynopsis>
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<para>
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<function>key</function> returns the index element of the
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current array position.
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<para>
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See also:
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<function>current</function>,
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<function>next</function>
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</refsect1>
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</refentry>
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<refentry id="function.ksort">
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<refnamediv>
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<refname>ksort</refname>
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<refpurpose>Sort an array by key</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>ksort</function></funcdef>
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<paramdef>array <parameter>array</parameter></paramdef>
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</funcsynopsis>
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<para>
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Sorts an array by key, maintaining key to data correlations. This
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is useful mainly for associative arrays.
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<example>
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<title><function>ksort</function> example</title>
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<programlisting>
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$fruits = array("d"=>"lemon","a"=>"orange","b"=>"banana","c"=>"apple");
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ksort($fruits);
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for(reset($fruits); $key = key($fruits); next($fruits)) {
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echo "fruits[$key] = ".$fruits[$key]."\n";
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}
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</programlisting></example>
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This example would display:
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<computeroutput>
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fruits[a] = orange
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fruits[b] = banana
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fruits[c] = apple
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fruits[d] = lemon
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</computeroutput>
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<simpara>
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See also <function>asort</function>, <function>arsort</function>,
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<function>sort</function>, and <function>rsort</function>.
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</refsect1>
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</refentry>
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<refentry id="function.list">
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<refnamediv>
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<refname>list</refname>
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<refpurpose>
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Assign variables as if they were an array
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</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>void <function>list</function></funcdef>
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<varargs>
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</funcsynopsis>
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<para>
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Like <function>array</function>, this is not really a function,
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but a language construct. <function>list</function> is used to
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assign a list of variables in one operation.
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<example>
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<title><function>list</function> example</title>
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<programlisting>
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<table>
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<tr>
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<th>Employee name</th>
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<th>Salary</th>
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</tr>
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<?php
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$result = mysql($conn, "SELECT id, name, salary FROM employees");
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while (list($id, $name, $salary) = mysql_fetch_row($result)) {
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print(" <tr>\n".
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" <td><a href=\"info.php3?id=$id\">$name</a></td>\n".
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" <td>$salary</td>\n".
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" </tr>\n");
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}
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?></table>
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</programlisting></example>
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<para>
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See also: <function>each</function>, <function>array</function>.
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</refsect1>
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</refentry>
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<refentry id="function.next">
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<refnamediv>
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<refname>next</refname>
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<refpurpose>Advance the internal array pointer of an array</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>mixed <function>next</function></funcdef>
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<paramdef>array <parameter>array</parameter></paramdef>
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</funcsynopsis>
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<para>
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Returns the array element in the next place that's pointed by the
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internal array pointer, or false if there are no more elements.
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<para>
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<function>next</function> behaves like <function>current</function>,
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with one difference. It advances the internal array pointer one
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place forward before returning the element. That means it returns
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the next array element and advances the internal array pointer by
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one. If advancing the internal array pointer results in going beyond
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the end of the element list, <function>next</function> returns false.
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<warning>
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<para>
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If the array contains empty elements then this function will return
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false for these elements as well. To properly traverse an array
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which may contain empty elements see the <function>each</function>
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function.
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</para>
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</warning>
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<para>
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See also:
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<function>current</function>, <function>end</function>
|
|
<function>prev</function> and <function>reset</function>
|
|
</refsect1>
|
|
</refentry>
|
|
|
|
<refentry id="function.pos">
|
|
<refnamediv>
|
|
<refname>pos</refname>
|
|
<refpurpose>Get the current element from an array</refpurpose>
|
|
</refnamediv>
|
|
<refsect1>
|
|
<title>Description</title>
|
|
<funcsynopsis>
|
|
<funcdef>mixed <function>pos</function></funcdef>
|
|
<paramdef>array <parameter>array</parameter></paramdef>
|
|
</funcsynopsis>
|
|
<simpara>
|
|
This is an alias for <function>current</function>.
|
|
<para>
|
|
See also:
|
|
<function>end</function>, <function>next</function>,
|
|
<function>prev</function> and <function>reset</function>.
|
|
</refsect1>
|
|
</refentry>
|
|
|
|
<refentry id="function.prev">
|
|
<refnamediv>
|
|
<refname>prev</refname>
|
|
<refpurpose>Rewind the internal array pointer</refpurpose>
|
|
</refnamediv>
|
|
<refsect1>
|
|
<title>Description</title>
|
|
<funcsynopsis>
|
|
<funcdef>mixed <function>prev</function></funcdef>
|
|
<paramdef>array <parameter>array</parameter></paramdef>
|
|
</funcsynopsis>
|
|
<para>
|
|
Returns the array element in the previous place that's pointed by
|
|
the internal array pointer, or false if there are no more elements.
|
|
|
|
<warning>
|
|
<para>
|
|
If the array contains empty elements then this function will return
|
|
false for these elements as well. To properly traverse an array
|
|
which may contain empty elements see the <function>each</function>
|
|
function.
|
|
</para>
|
|
</warning>
|
|
|
|
<para>
|
|
<function>prev</function> behaves just like
|
|
<function>next</function>, except it rewinds the internal array
|
|
pointer one place instead of advancing it.
|
|
|
|
<para>
|
|
See also:
|
|
<function>current</function>, <function>end</function>
|
|
<function>next</function> and <function>reset</function>
|
|
</refsect1>
|
|
</refentry>
|
|
|
|
<refentry id="function.range">
|
|
<refnamediv>
|
|
<refname>range</refname>
|
|
<refpurpose>Create an array containing a range of integers</refpurpose>
|
|
</refnamediv>
|
|
<refsect1>
|
|
<title>Description</title>
|
|
<funcsynopsis>
|
|
<funcdef>array <function>range</function></funcdef>
|
|
<paramdef>int <parameter>low</parameter></paramdef>
|
|
<paramdef>int <parameter>high</parameter></paramdef>
|
|
</funcsynopsis>
|
|
<para>
|
|
<function>range</function> returns an array of integers from
|
|
<parameter>low</parameter> to <parameter>high</parameter>,
|
|
inclusive.
|
|
<para>
|
|
See <function>shuffle</function> for an example of its use.
|
|
</refsect1>
|
|
</refentry>
|
|
|
|
<refentry id="function.reset">
|
|
<refnamediv>
|
|
<refname>reset</refname>
|
|
<refpurpose>
|
|
Set the internal pointer of an array to its first element
|
|
</refpurpose>
|
|
</refnamediv>
|
|
<refsect1>
|
|
<title>Description</title>
|
|
<funcsynopsis>
|
|
<funcdef>mixed <function>reset</function></funcdef>
|
|
<paramdef>array <parameter>array</parameter></paramdef>
|
|
</funcsynopsis>
|
|
<para>
|
|
<function>reset</function> rewinds <parameter>array</parameter>'s
|
|
internal pointer to the first element.
|
|
<para>
|
|
<function>reset</function> returns the value of the first array
|
|
element.
|
|
<para>
|
|
See also:
|
|
<function>current</function>, <function>each</function>, <function>next</function>
|
|
<function>prev</function> and <function>reset</function>
|
|
</refsect1>
|
|
</refentry>
|
|
|
|
<refentry id="function.rsort">
|
|
<refnamediv>
|
|
<refname>rsort</refname>
|
|
<refpurpose>Sort an array in reverse order</refpurpose>
|
|
</refnamediv>
|
|
<refsect1>
|
|
<title>Description</title>
|
|
<funcsynopsis>
|
|
<funcdef>void <function>rsort</function></funcdef>
|
|
<paramdef>array <parameter>array</parameter></paramdef>
|
|
</funcsynopsis>
|
|
<para>
|
|
This function sorts an array in reverse order (highest to lowest).
|
|
<example>
|
|
<title><function>rsort</function> example</title>
|
|
<programlisting>
|
|
$fruits = array("lemon","orange","banana","apple");
|
|
rsort($fruits);
|
|
for (reset($fruits); list($key,$value) = each($fruits); ) {
|
|
echo "fruits[$key] = ", $value, "\n";
|
|
}
|
|
</programlisting>
|
|
</example>
|
|
|
|
This example would display:
|
|
|
|
<computeroutput>
|
|
fruits[0] = orange
|
|
fruits[1] = lemon
|
|
fruits[2] = banana
|
|
fruits[3] = apple
|
|
</computeroutput>
|
|
|
|
The fruits have been sorted in reverse alphabetical order.
|
|
|
|
<para>
|
|
See also <function>arsort</function>, <function>asort</function>,
|
|
<function>ksort</function>, <function>sort</function> and <function>usort</function>.
|
|
</refsect1>
|
|
</refentry>
|
|
|
|
<refentry id="function.shuffle">
|
|
<refnamediv>
|
|
<refname>shuffle</refname>
|
|
<refpurpose>Shuffle an array</refpurpose>
|
|
</refnamediv>
|
|
<refsect1>
|
|
<title>Description</title>
|
|
<funcsynopsis>
|
|
<funcdef>void <function>shuffle</function></funcdef>
|
|
<paramdef>array <parameter>array</parameter></paramdef>
|
|
</funcsynopsis>
|
|
<para>
|
|
This function shuffles (randomizes the order of the elements in)
|
|
an array.
|
|
<example>
|
|
<title><function>shuffle</function> example</title>
|
|
<programlisting>
|
|
$numbers = range(1,20);
|
|
srand(time());
|
|
shuffle($numbers);
|
|
while (list(,$number) = each($numbers)) {
|
|
echo "$number ";
|
|
}
|
|
</programlisting></example>
|
|
<para>
|
|
See also <function>arsort</function>, <function>asort</function>,
|
|
<function>ksort</function>, <function>rsort</function>,
|
|
<function>sort</function> and <function>usort</function>.
|
|
</refsect1>
|
|
</refentry>
|
|
|
|
<refentry id="function.sizeof">
|
|
<refnamediv>
|
|
<refname>sizeof</refname>
|
|
<refpurpose>Get the number of elements in an array</refpurpose>
|
|
</refnamediv>
|
|
<refsect1>
|
|
<title>Description</title>
|
|
<funcsynopsis>
|
|
<funcdef>int <function>sizeof</function></funcdef>
|
|
<paramdef>array <parameter>array</parameter></paramdef>
|
|
</funcsynopsis>
|
|
<para>
|
|
Returns the number of elements in the array.
|
|
<para>
|
|
See also:
|
|
<function>count</function>
|
|
</refsect1>
|
|
</refentry>
|
|
|
|
<refentry id="function.sort">
|
|
<refnamediv>
|
|
<refname>sort</refname>
|
|
<refpurpose>Sort an array</refpurpose>
|
|
</refnamediv>
|
|
<refsect1>
|
|
<title>Description</title>
|
|
<funcsynopsis>
|
|
<funcdef>void <function>sort</function></funcdef>
|
|
<paramdef>array <parameter>array</parameter></paramdef>
|
|
</funcsynopsis>
|
|
<para>
|
|
This function sorts an array. Elements will be arranged from lowest to
|
|
highest when this function has completed.
|
|
<example>
|
|
<title><function>sort</function> example</title>
|
|
<programlisting>
|
|
$fruits = array("lemon","orange","banana","apple");
|
|
sort($fruits);
|
|
for(reset($fruits); $key = key($fruits); next($fruits)) {
|
|
echo "fruits[$key] = ".$fruits[$key]."\n";
|
|
}
|
|
</programlisting></example>
|
|
This example would display:
|
|
<computeroutput>
|
|
fruits[0] = apple
|
|
fruits[1] = banana
|
|
fruits[2] = lemon
|
|
fruits[3] = orange
|
|
</computeroutput>
|
|
The fruits have been sorted in alphabetical order.
|
|
<para>
|
|
See also <function>arsort</function>, <function>asort</function>,
|
|
<function>ksort</function>, <function>rsort</function>, and <function>usort</function>.
|
|
</refsect1>
|
|
</refentry>
|
|
|
|
<refentry id="function.uasort">
|
|
<refnamediv>
|
|
<refname>uasort</refname>
|
|
<refpurpose>Sort an array with a user-defined comparison function and maintain index association</refpurpose>
|
|
</refnamediv>
|
|
<refsect1>
|
|
<title>Description</title>
|
|
<funcsynopsis>
|
|
<funcdef>void <function>uasort</function></funcdef>
|
|
<paramdef>array <parameter>array</parameter></paramdef>
|
|
<paramdef>function <parameter>cmp_function</parameter></paramdef>
|
|
</funcsynopsis>
|
|
<para>
|
|
This function sorts an array such that array indices maintain their
|
|
correlation with the array elements they are associated with. This is
|
|
used mainly when sorting associative arrays where the actual element
|
|
order is significant. The comparison function is user-defined.
|
|
</refsect1>
|
|
</refentry>
|
|
|
|
<refentry id="function.uksort">
|
|
<refnamediv>
|
|
<refname>uksort</refname>
|
|
<refpurpose>Sort an array by keys using a user-defined comparison function</refpurpose>
|
|
</refnamediv>
|
|
<refsect1>
|
|
<title>Description</title>
|
|
<funcsynopsis>
|
|
<funcdef>void <function>uksort</function></funcdef>
|
|
<paramdef>array <parameter>array</parameter></paramdef>
|
|
<paramdef>function <parameter>cmp_function</parameter></paramdef>
|
|
</funcsynopsis>
|
|
<para>
|
|
This function will sort the keys of an array using a
|
|
user-supplied comparison function. If the array you wish to sort
|
|
needs to be sorted by some non-trivial criteria, you should use
|
|
this function.
|
|
|
|
<example>
|
|
<title><function>uksort</function> example</title>
|
|
<programlisting>
|
|
function mycompare($a, $b) {
|
|
if ($a == $b) return 0;
|
|
return ($a > $b) ? -1 : 1;
|
|
}
|
|
$a = array(4 => "four", 3 => "three", 20 => "twenty", 10 => "ten");
|
|
uksort($a, mycompare);
|
|
while(list($key, $value) = each($a)) {
|
|
echo "$key: $value\n";
|
|
}
|
|
</programlisting></example>
|
|
|
|
This example would display:
|
|
|
|
<computeroutput>
|
|
20: twenty
|
|
10: ten
|
|
4: four
|
|
3: three
|
|
</computeroutput>
|
|
|
|
<para>
|
|
See also <function>arsort</function>, <function>asort</function>,
|
|
<function>uasort</function>, <function>ksort</function>,
|
|
<function>rsort</function> and <function>sort</function>.
|
|
|
|
</refsect1>
|
|
</refentry>
|
|
|
|
<refentry id="function.usort">
|
|
<refnamediv>
|
|
<refname>usort</refname>
|
|
<refpurpose>Sort an array by values using a user-defined comparison function</refpurpose>
|
|
</refnamediv>
|
|
<refsect1>
|
|
<title>Description</title>
|
|
<funcsynopsis>
|
|
<funcdef>void <function>usort</function></funcdef>
|
|
<paramdef>array <parameter>array</parameter></paramdef>
|
|
<paramdef>function <parameter>cmp_function</parameter></paramdef>
|
|
</funcsynopsis>
|
|
<para>
|
|
This function will sort an array by its values using a
|
|
user-supplied comparison function. If the array you wish to sort
|
|
needs to be sorted by some non-trivial criteria, you should use
|
|
this function.
|
|
<para>
|
|
The comparison function must return an integer less than, equal to, or
|
|
greater than zero if the first argument is considered to be respectively
|
|
less than, equal to, or greater than the second. If two members compare
|
|
as equal, their order in the sorted array is undefined.
|
|
<example>
|
|
<title><function>usort</function> example</title>
|
|
<programlisting>
|
|
function cmp($a,$b) {
|
|
if ($a == $b) return 0;
|
|
return ($a > $b) ? -1 : 1;
|
|
}
|
|
$a = array(3,2,5,6,1);
|
|
usort($a, cmp);
|
|
while(list($key,$value) = each($a)) {
|
|
echo "$key: $value\n";
|
|
}
|
|
</programlisting></example>
|
|
This example would display:
|
|
<computeroutput>
|
|
0: 6
|
|
1: 5
|
|
2: 3
|
|
3: 2
|
|
4: 1
|
|
</computeroutput>
|
|
|
|
<note>
|
|
<para>
|
|
Obviously in this trivial case the <function>rsort</function> function
|
|
would be more appropriate.
|
|
</para>
|
|
</note>
|
|
|
|
<warning>
|
|
<para>
|
|
The underlying quicksort function in some C libraries (such as on
|
|
Solaris systems) may cause PHP to crash if the comparison function
|
|
does not return consistent values.
|
|
</para>
|
|
</warning>
|
|
|
|
<para>
|
|
See also:
|
|
<function>arsort</function>, <function>asort</function>,
|
|
<function>ksort</function>, <function>rsort</function> and
|
|
<function>sort</function>.
|
|
|
|
</refsect1>
|
|
</refentry>
|
|
|
|
</reference>
|
|
|
|
<!-- Keep this comment at the end of the file
|
|
Local variables:
|
|
mode: sgml
|
|
sgml-omittag:t
|
|
sgml-shorttag:t
|
|
sgml-minimize-attributes:nil
|
|
sgml-always-quote-attributes:t
|
|
sgml-indent-step:1
|
|
sgml-indent-data:t
|
|
sgml-parent-document:nil
|
|
sgml-default-dtd-file:"../manual.ced"
|
|
sgml-exposed-tags:nil
|
|
sgml-local-catalogs:nil
|
|
sgml-local-ecat-files:nil
|
|
End:
|
|
-->
|