Arrays array Create an array array array Returns an array of the parameters. The parameters can be given an index with the => operator. array is a language construct used to represent literal arrays, and not a regular function. The following example demonstrates how to create a two-dimensional array, how to specify keys for associative arrays, and how to skip-and-continue numeric indices in normal arrays. $fruits = array( "fruits" => array("a"=>"orange","b"=>"banana","c"=>"apple"), "numbers" => array(1, 2, 3, 4, 5, 6), "holes" => array("first", 5 => "second", "third") ); See also: list. array_walk Apply a user function to every member of an array. int array_walk array arr string func Applies the function named by func to each element of arr. The elements are passed as the first argument of func; if func requires more than one argument, a warning will be generated each time array_walk calls func. These warnings may be suppressed by prepending the '@' sign to the array_walk call, or by using error_reporting. func will actually be working with the elements of arr, so any changes made to those elements will be made in the array itself. $fruits = array("d"=>"lemon","a"=>"orange","b"=>"banana","c"=>"apple"); function test_alter( $item1 ) { $item1 = 'bogus'; } function test_print( $item2 ) { echo "$item2<br>\n"; } array_walk( $fruits, 'test_print' ); array_walk( $fruits, 'test_alter' ); array_walk( $fruits, 'test_print' ); See also each and list. arsort Sort an array in reverse order and maintain index association void arsort array array 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. $fruits = array("d"=>"lemon","a"=>"orange","b"=>"banana","c"=>"apple"); arsort($fruits); for(reset($fruits); $key = key($fruits); next($fruits)) { echo "fruits[$key] = ".$fruits[$key]."\n"; } This example would display: fruits[a] = orange fruits[d] = lemon fruits[b] = banana fruits[c] = apple The fruits have been sorted in reverse alphabetical order, and the index associated with each element has been maintained. See also: asort, rsort, ksort, and sort. asort Sort an array and maintain index association void asort array array 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. $fruits = array("d"=>"lemon","a"=>"orange","b"=>"banana","c"=>"apple"); asort($fruits); for(reset($fruits); $key = key($fruits); next($fruits)) { echo "fruits[$key] = ".$fruits[$key]."\n"; } This example would display: fruits[c] = apple fruits[b] = banana fruits[d] = lemon fruits[a] = orange The fruits have been sorted in alphabetical order, and the index associated with each element has been maintained. See also arsort, rsort, ksort, and sort. count count elements in a variable int count mixed var Returns the number of elements in var, which is typically an array (since anything else will have one element). Returns 1 if the variable is not an array. Returns 0 if the variable is not set. count may return 0 for a variable that isn't set, but it may also return 0 for a variable that has been initialized with an empty array. Use isset to test if a variable is set. See also: sizeof, isset, and is_array. current Return the current element in an array mixed current array array Every array has an internal pointer to its "current" element, which is initialized to the first element inserted into the array. The current function simply returns the array element that's currently being pointed by the internal pointer. It does not move the pointer in any way. If the internal pointer points beyond the end of the elements list, current returns false. If the array contains empty elements (0 or "", the empty string) then this function will return false for these elements as well. This makes it impossible to determine if you are really at the end of the list in such an array using current. To properly traverse an array that may contain empty elements, use the each function. See also: end, next, prev and reset. each Return the next key and value pair from an array array each array array Returns the current key and value pair from the array array and advances the array cursor. This pair is returned in a four-element array, with the keys 0, 1, key, and value. Elements 0 and key contain the key name of the array element, and 1 and value contain the data. If the internal pointer for the array points past the end of the array contents, each returns false. $foo = array( "bob", "fred", "jussi", "jouni" ); $bar = each( $foo ); $bar now contains the following key/value pairs: 0 => 0 1 => 'bob' key => 0 value => 'bob' $foo = array( "Robert" => "Bob", "Seppo" => "Sepi" ); $bar = each( $foo ); $bar now contains the following key/value pairs: 0 => 'Robert' 1 => 'Bob' key => 'Robert' value => 'Bob' each is typically used in conjunction with list to traverse an array; for instance, $HTTP_POST_VARS: echo "Values submitted via POST method:<br>"; while (list($key, $val) = each($HTTP_POST_VARS)) { echo "$key => $val<br>"; } After each has executed, the array cursor will be left on the next element of the array, or on the last element if it hits the end of the array. See also key, list, current, reset, next, and prev. end Set the internal pointer of an array to its last element end array array end advances array's internal pointer to the last element. See also: current, each, end next and reset key Fetch a key from an associative array mixed key array array key returns the index element of the current array position. See also: current, next ksort Sort an array by key int ksort array array Sorts an array by key, maintaining key to data correlations. This is useful mainly for associative arrays. $fruits = array("d"=>"lemon","a"=>"orange","b"=>"banana","c"=>"apple"); ksort($fruits); for(reset($fruits); $key = key($fruits); next($fruits)) { echo "fruits[$key] = ".$fruits[$key]."\n"; } This example would display: fruits[a] = orange fruits[b] = banana fruits[c] = apple fruits[d] = lemon See also asort, arsort, sort, and rsort. list Assign variables as if they were an array void list Like array, this is not really a function, but a language construct. list is used to assign a list of variables in one operation. <table> <tr> <th>Employee name</th> <th>Salary</th> </tr> <?php $result = mysql($conn, "SELECT id, name, salary FROM employees"); while (list($id, $name, $salary) = mysql_fetch_row($result)) { print(" <tr>\n". " <td><a href=\"info.php3?id=$id\">$name</a></td>\n". " <td>$salary</td>\n". " </tr>\n"); } ?></table> See also: each, array. next Advance the internal array pointer of an array mixed next array array Returns the array element in the next place that's pointed by the internal array pointer, or false if there are no more elements. next behaves like current, with one difference. It advances the internal array pointer one place forward before returning the element. That means it returns the next array element and advances the internal array pointer by one. If advancing the internal array pointer results in going beyond the end of the element list, next returns false. 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 each function. See also: current, end prev and reset pos Get the current element from an array mixed pos array array This is an alias for current. See also: end, next, prev and reset. prev Rewind the internal array pointer mixed prev array array Returns the array element in the previous place that's pointed by the internal array pointer, or false if there are no more elements. 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 each function. prev behaves just like next, except it rewinds the internal array pointer one place instead of advancing it. See also: current, end next and reset range Create an array containing a range of integers array range int low int high range returns an array of integers from low to high, inclusive. See shuffle for an example of its use. reset Set the internal pointer of an array to its first element mixed reset array array reset rewinds array's internal pointer to the first element. reset returns the value of the first array element. See also: current, each, next prev and reset rsort Sort an array in reverse order void rsort array array This function sorts an array in reverse order (highest to lowest). $fruits = array("lemon","orange","banana","apple"); rsort($fruits); for (reset($fruits); list($key,$value) = each($fruits); ) { echo "fruits[$key] = ", $value, "\n"; } This example would display: fruits[0] = orange fruits[1] = lemon fruits[2] = banana fruits[3] = apple The fruits have been sorted in reverse alphabetical order. See also arsort, asort, ksort, sort and usort. shuffle Shuffle an array void shuffle array array This function shuffles (randomizes the order of the elements in) an array. $numbers = range(1,20); srand(time()); shuffle($numbers); while (list(,$number) = each($numbers)) { echo "$number "; } See also arsort, asort, ksort, rsort, sort and usort. sizeof Get the number of elements in an array int sizeof array array Returns the number of elements in the array. See also: count sort Sort an array void sort array array This function sorts an array. Elements will be arranged from lowest to highest when this function has completed. $fruits = array("lemon","orange","banana","apple"); sort($fruits); for(reset($fruits); $key = key($fruits); next($fruits)) { echo "fruits[$key] = ".$fruits[$key]."\n"; } This example would display: fruits[0] = apple fruits[1] = banana fruits[2] = lemon fruits[3] = orange The fruits have been sorted in alphabetical order. See also arsort, asort, ksort, rsort, and usort. uasort Sort an array with a user-defined comparison function and maintain index association void uasort array array function cmp_function 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. uksort Sort an array by keys using a user-defined comparison function void uksort array array function cmp_function 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. 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: $value\n"; } This example would display: 20: twenty 10: ten 4: four 3: three See also arsort, asort, uasort, ksort, rsort and sort. usort Sort an array by values using a user-defined comparison function void usort array array function cmp_function This function will sort an array by its values using a user-supplied comparison function. If the array you wish to sort needs to be sorted by some non-trivial criteria, you should use this function. The comparison function must return an integer less than, equal to, or greater than zero if the first argument is considered to be respectively less than, equal to, or greater than the second. If two members compare as equal, their order in the sorted array is undefined. function cmp($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"; } This example would display: 0: 6 1: 5 2: 3 3: 2 4: 1 Obviously in this trivial case the rsort function would be more appropriate. 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. See also: arsort, asort, ksort, rsort and sort.