Arrays These functions allow you to interact with and manipulate arrays in various ways. Arrays are essential for storing, managing, and operating on sets of variables. Simple and multi-dimensional arrays are supported, and may be either user created or created by another function. There are specific database handling functions for populating arrays from database queries, and several functions return arrays. See also is_array, explode, implode, split and join. array Create an array array array mixed ... 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. Syntax "index => values", separated by commas, define index and values. index may be of type string or numeric. When index is omitted, a integer index is automatically generated, starting at 0. If index is an integer, next generated index will be the biggest integer index + 1. Note that when two identical index are defined, the last overwrite the first. 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") ); $array = array( 1, 1, 1, 1, 1, 8=>1, 4=>1, 19, 3=>13); print_r($array); which will display : Array ( [0] => 1 [1] => 1 [2] => 1 [3] => 13 [4] => 1 [8] => 1 [9] => 19 ) Note that index '3' is defined twice, and keep its final value of 13. Index 4 is defined after index 8, and next generated index (value 19) is 9, since biggest index was 8. This example creates a 1-based array. $firstquarter = array(1 => 'January', 'February', 'March'); print_r($firstquarter); which will display : Array ( [1] => 'January' [2] => 'February' [3] => 'March' ) See also: list. array_count_values Counts all the values of an array array array_count_values array input Array_count_values returns an array using the values of the input array as keys and their frequency in input as values. $array = array (1, "hello", 1, "world", "hello"); array_count_values ($array); // returns array (1=>2, "hello"=>2, "world"=>1) array_diff Computes the difference of arrays array array_diff array array1 array array2 array ... Array_diff returns an array containing all the values of array1 that are not present in any of the other arguments. Note that keys are preserved. $array1 = array ("a" => "green", "red", "blue"); $array2 = array ("b" => "green", "yellow", "red"); $result = array_diff ($array1, $array2); This makes $result have array ("blue"); See also array_intersect. array_filter Filters elements of an array using a callback function array array_filter array input mixed callback Array_filter returns an array containing all the elements of input filtered according a callback function. If the input is an associative array the keys are preserved. function odd($var) { return ($var % 2 == 1); } function even($var) { return ($var % 2 == 0); } $array1 = array ("a"=>1, "b"=>2, "c"=>3, "d"=>4, "e"=>5); $array2 = array (6, 7, 8, 9, 10, 11, 12); $odd_arr = array_filter($array1, "odd"); $even_arr = array_filter($array2, "even"); This makes $odd_arr have array ("a"=>1, "c"=>3, "e"=>5);, and $even_arr have array (6, 8, 10, 12);, See also array_map, array_reduce. array_flip Flip all the values of an array array array_flip array trans Array_flip returns an array in flip order. $trans = array_flip ($trans); $original = strtr ($str, $trans); array_intersect Computes the intersection of arrays array array_intersect array array1 array array2 array ... Array_intersect returns an array containing all the values of array1 that are present in all the arguments. Note that keys are preserved. $array1 = array ("a" => "green", "red", "blue"); $array2 = array ("b" => "green", "yellow", "red"); $result = array_intersect ($array1, $array2); This makes $result have array ("a" => "green", "red"); See also array_diff. array_keys Return all the keys of an array array array_keys array input mixed search_value Array_keys returns the keys, numeric and string, from the input array. If the optional search_value is specified, then only the keys for that value are returned. Otherwise, all the keys from the input are returned. $array = array (0 => 100, "color" => "red"); array_keys ($array); // returns array (0, "color") $array = array ("blue", "red", "green", "blue", "blue"); array_keys ($array, "blue"); // returns array (0, 3, 4) $array = array ("color" => array("blue", "red", "green"), "size" => array("small", "medium", "large")); array_keys ($array); // returns array ("color", "size") This function was added to PHP 4, below is an implementation for those still using PHP 3. function array_keys ($arr, $term="") { $t = array(); while (list($k,$v) = each($arr)) { if ($term && $v != $term) continue; $t[] = $k; } return $t; } See also array_values. array_map Applies the callback to the elements of the given arrays array array_map mixed callback array arr1 array arr2... Array_map returns an array containing all the elements of arr1 after applying the callback function to each one. The number of parameters that the callback function accepts should match the number of arrays passed to the array_map function cube($n) { return $n*$n*$n; } $a = array(1, 2, 3, 4, 5); $b = array_map("cube", $a); This will result in $b containing array (1, 8, 27, 64, 125); function show_Spanish($n, $m) { return "The number $n is called $m in Spanish"; } function map_Spanish($n, $m) { return array ($n => $m); } $a = array(1, 2, 3, 4, 5); $b = array("uno", "dos", "tres", "cuatro", "cinco"); $c = array_map("show_Spanish", $a, $b); print_r($c); // will output: // Array // ( // [0] => The number 1 is called uno in Spanish // [1] => The number 2 is called dos in Spanish // [2] => The number 3 is called tres in Spanish // [3] => The number 4 is called cuatro in Spanish // [4] => The number 5 is called cinco in Spanish // ) $d = array_map("map_Spanish", $a , $b); print_r($d); // will output: // Array // ( // [0] => Array // ( // [1] => uno // ) // // [1] => Array // ( // [2] => dos // ) // // [2] => Array // ( // [3] => tres // ) // // [3] => Array // ( // [4] => cuatro // ) // // [4] => Array // ( // [5] => cinco // ) // // ) Usually when using two or more arrays, they should be of equal length because the callback function is applied in parallel to the corresponding elements. If the arrays are of unequal length, the shortest one will be extended with empty elements. An interesting use of this function is to construct an array of arrays, which can be easily performed by using null as the name of the callback function $a = array(1, 2, 3, 4, 5); $b = array("one", "two", "three", "four", "five"); $c = array("uno", "dos", "tres", "cuatro", "cinco"); $d = array_map(null, $a, $b, $c); print_r($d); // will output: // Array // ( // [0] => Array // ( // [0] => 1 // [1] => one // [2] => uno // ) // // [1] => Array // ( // [0] => 2 // [1] => two // [2] => dos // ) // // [2] => Array // ( // [0] => 3 // [1] => three // [2] => tres // ) // // [3] => Array // ( // [0] => 4 // [1] => four // [2] => cuatro // ) // // [4] => Array // ( // [0] => 5 // [1] => five // [2] => cinco // ) // // ) See also array_filter, array_reduce. array_merge Merge two or more arrays array array_merge array array1 array array2 array ... Array_merge merges the elements of two or more arrays together so that the values of one are appended to the end of the previous one. It returns the resulting array. If the input arrays have the same string keys, then the later value for that key will overwrite the previous one. If, however, the arrays have the same numeric key, the later value will not overwrite the original value, but will be appended. $array1 = array ("color" => "red", 2, 4); $array2 = array ("a", "b", "color" => "green", "shape" => "trapezoid", 4); array_merge ($array1, $array2); Resulting array will be array("color" => "green", 2, 4, "a", "b", "shape" => "trapezoid", 4). See also array_merge_recursive. array_merge_recursive Merge two or more arrays recursively array array_merge_recursive array array1 array array2 array ... Array_merge_recursive merges the elements of two or more arrays together so that the values of one are appended to the end of the previous one. It returns the resulting array. If the input arrays have the same string keys, then the values for these keys are merged together into an array, and this is done recursively, so that if one of the values is an array itself, the function will merge it with a corresponding entry in another array too. If, however, the arrays have the same numeric key, the later value will not overwrite the original value, but will be appended. $ar1 = array ("color" => array ("favorite" => "red"), 5); $ar2 = array (10, "color" => array ("favorite" => "green", "blue")); $result = array_merge_recursive ($ar1, $ar2); Resulting array will be array ("color" => array ("favorite" => array ("red", "green"), "blue"), 5, 10). See also array_merge. array_multisort Sort multiple or multi-dimensional arrays bool array_multisort array ar1 mixed arg mixed ... array ... Array_multisort can be used to sort several arrays at once or a multi-dimensional array according by one of more dimensions. It maintains key association when sorting. The input arrays are treated as columns of a table to be sorted by rows - this resembles the functionality of SQL ORDER BY clause. The first array is the primary one to sort by. The rows (values) in that array that compare the same are sorted by the next input array, and so on. The argument structure of this function is a bit unusual, but flexible. The very first argument has to be an array. Subsequently, each argument can be either an array or a sorting flag from the following lists. Sorting order flags: SORT_ASC - sort in ascending order SORT_DESC - sort in descending order Sorting type flags: SORT_REGULAR - compare items normally SORT_NUMERIC - compare items numerically SORT_STRING - compare items as strings No two sorting flags of the same type can be specified after each array. The sortings flags specified after an array argument apply only to that array - they are reset to default SORT_ASC and SORT_REGULAR after before each new array argument. Returns TRUE on success, FALSE on failure. $ar1 = array ("10", 100, 100, "a"); $ar2 = array (1, 3, "2", 1); array_multisort ($ar1, $ar2); In this example, after sorting, the first array will contain 10, "a", 100, 100. The second array will contain 1, 1, 2, "3". The entries in the second array corresponding to the identical entries in the first array (100 and 100) were sorted as well. $ar = array (array ("10", 100, 100, "a"), array (1, 3, "2", 1)); array_multisort ($ar[0], SORT_ASC, SORT_STRING, $ar[1], SORT_NUMERIC, SORT_DESC); In this example, after sorting, the first array will contain 10, 100, 100, "a" (it was sorted as strings in ascending order), and the second one will contain 1, 3, "2", 1 (sorted as numbers, in descending order). array_pad Pad array to the specified length with a value array array_pad array input int pad_size mixed pad_value Array_pad returns a copy of the input padded to size specified by pad_size with value pad_value. If pad_size is positive then the array is padded on the right, if it's negative then on the left. If the absolute value of pad_size is less than or equal to the length of the input then no padding takes place. $input = array (12, 10, 9); $result = array_pad ($input, 5, 0); // result is array (12, 10, 9, 0, 0) $result = array_pad ($input, -7, -1); // result is array (-1, -1, -1, -1, 12, 10, 9) $result = array_pad ($input, 2, "noop"); // not padded array_pop Pop the element off the end of array mixed array_pop array array Array_pop pops and returns the last value of the array, shortening the array by one element. If array is empty (or is not an array), NULL will be returned. $stack = array ("orange", "apple", "raspberry"); $fruit = array_pop ($stack); After this, $stack has only 2 elements: "orange" and "apple", and $fruit has "raspberry". See also array_push, array_shift, and array_unshift. array_push Push one or more elements onto the end of array int array_push array array mixed var mixed ... Array_push treats array as a stack, and pushes the passed variables onto the end of array. The length of array increases by the number of variables pushed. Has the same effect as: $array[] = $var; repeated for each var. Returns the new number of elements in the array. $stack = array (1, 2); array_push ($stack, "+", 3); This example would result in $stack having 4 elements: 1, 2, "+", and 3. See also: array_pop, array_shift, and array_unshift. array_rand Pick one or more random entries out of an array mixed array_rand array input int num_req Array_rand is rather useful when you want to pick one or more random entries out of an array. It takes an input array and an optional argument num_req which specifies how many entries you want to pick - if not specified, it defaults to 1. If you are picking only one entry, array_rand returns the key for a random entry. Otherwise, it returns an array of keys for the random entries. This is done so that you can pick random keys as well as values out of the array. Don't forget to call srand to seed the random number generator. srand ((double) microtime() * 10000000); $input = array ("Neo", "Morpheus", "Trinity", "Cypher", "Tank"); $rand_keys = array_rand ($input, 2); print $input[$rand_keys[0]]."\n"; print $input[$rand_keys[1]]."\n"; array_reverse Return an array with elements in reverse order array array_reverse array array bool preserve_keys Array_reverse takes input array and returns a new array with the order of the elements reversed, preserving the keys if preserve_keys is TRUE. $input = array ("php", 4.0, array ("green", "red")); $result = array_reverse ($input); $result_keyed = array_reverse ($input, TRUE); This makes $result have array (array ("green", "red"), 4.0, "php"). But $result2[0] is still "php". The second parameter was added in PHP 4.0.3. array_reduce Iteratively reduce the array to a single value using a callback function mixed array_reduce array input mixed callback int initial Array_reduce applies iteratively the callback function to the elements of the array input, so as to reduce the array to a single value. If the optional intial is avaliable, it will be used at the beginning of the process, or as a final result in case the array is empty. function rsum($v, $w) { $v += $w; return $v; } function rmul($v, $w) { $v *= $w; return $v; } $a = array(1, 2, 3, 4, 5); $x = array(); $b = array_reduce($a, "rsum"); $c = array_reduce($a, "rmul", 10); $d = array_reduce($x, "rsum", 1); This will result in $b containing 15, $c containing 1200 (= 1*2*3*4*5*10), and $d containing 1. See also array_filter, array_map. array_shift Pop an element off the beginning of array mixed array_shift array array Array_shift shifts the first value of the array off and returns it, shortening the array by one element and moving everything down. If array is empty (or is not an array), NULL will be returned. $args = array ("-v", "-f"); $opt = array_shift ($args); This would result in $args having one element "-f" left, and $opt being "-v". See also array_unshift, array_push, and array_pop. array_slice Extract a slice of the array array array_slice array array int offset int length Array_slice returns a sequence of elements from the array specified by the offset and length parameters. If offset is positive, the sequence will start at that offset in the array. If offset is negative, the sequence will start that far from the end of the array. If length is given and is positive, then the sequence will have that many elements in it. If length is given and is negative then the sequence will stop that many elements from the end of the array. If it is omitted, then the sequence will have everything from offset up until the end of the array. $input = array ("a", "b", "c", "d", "e"); $output = array_slice ($input, 2); // returns "c", "d", and "e" $output = array_slice ($input, 2, -1); // returns "c", "d" $output = array_slice ($input, -2, 1); // returns "d" $output = array_slice ($input, 0, 3); // returns "a", "b", and "c" See also array_splice. array_splice Remove a portion of the array and replace it with something else array array_splice array input int offset int length array replacement Array_splice removes the elements designated by offset and length from the input array, and replaces them with the elements of the replacement array, if supplied. If offset is positive then the start of removed portion is at that offset from the beginning of the input array. If offset is negative then it starts that far from the end of the input array. If length is omitted, removes everything from offset to the end of the array. If length is specified and is positive, then that many elements will be removed. If length is specified and is negative then the end of the removed portion will be that many elements from the end of the array. Tip: to remove everything from offset to the end of the array when replacement is also specified, use count($input) for length. If replacement array is specified, then the removed elements are replaced with elements from this array. If offset and length are such that nothing is removed, then the elements from the replacement array are inserted in the place specified by the offset. Tip: if the replacement is just one element it is not necessary to put array() around it, unless the element is an array itself. The following equivalences hold: array_push ($input, $x, $y) array_splice ($input, count ($input), 0, array ($x, $y)) array_pop ($input) array_splice ($input, -1) array_shift ($input) array_splice ($input, 0, 1) array_unshift ($input, $x, $y) array_splice ($input, 0, 0, array ($x, $y)) $a[$x] = $y array_splice ($input, $x, 1, $y) Returns the array consisting of removed elements. $input = array ("red", "green", "blue", "yellow"); array_splice ($input, 2); // $input is now array ("red", "green") array_splice ($input, 1, -1); // $input is now array ("red", "yellow") array_splice ($input, 1, count($input), "orange"); // $input is now array ("red", "orange") array_splice ($input, -1, 1, array("black", "maroon")); // $input is now array ("red", "green", // "blue", "black", "maroon") See also array_slice. array_sum Calculate the sum of values in an array. mixed array_sum array arr Array_sum returns the sum of values in an array as an integer or float. $a = array(2,4,6,8); echo "sum(a) = ".array_sum($a)."\n"; // prints: sum(a) = 20 $b = array("a"=>1.2,"b"=>2.3,"c"=>3.4); echo "sum(b) = ".array_sum($b)."\n"; // prints: sum(b) = 6.9 array_unique Removes duplicate values from an array array array_unique array array Array_unique takes input array and returns a new array without duplicate values. Note that keys are preserved. $input = array ("a" => "green", "red", "b" => "green", "blue", "red"); $result = array_unique ($input); This makes $result have array ("a" => "green", "red", "blue");. array_unshift Push one or more elements onto the beginning of array int array_unshift array array mixed var mixed ... Array_unshift prepends passed elements to the front of the array. Note that the list of elements is prepended as a whole, so that the prepended elements stay in the same order. Returns the new number of elements in the array. $queue = array ("p1", "p3"); array_unshift ($queue, "p4", "p5", "p6"); This would result in $queue having 5 elements: "p4", "p5", "p6", "p1", and "p3". See also array_shift, array_push, and array_pop. array_values Return all the values of an array array array_values array input array_values returns all the values from the input array. $array = array ("size" => "XL", "color" => "gold"); array_values ($array); // returns array ("XL", "gold") This function was added to PHP 4, below is an implementation for those still using PHP 3. function array_values ($arr) { $t = array(); while (list($k, $v) = each ($arr)) { $t[] = $v; } return $t; } array_walk Apply a user function to every member of an array int array_walk array arr string func mixed userdata Applies the function named by func to each element of arr. func will be passed array value as the first parameter and array key as the second parameter. If userdata is supplied, it will be passed as the third parameter to the user function. If func requires more than two or three arguments, depending on userdata, 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. If func needs to be working with the actual values of the array, specify that the first parameter of func should be passed by reference. Then any changes made to those elements will be made in the array itself. Passing the key and userdata to func was added in 4.0. In PHP 4 reset needs to be called as necessary since array_walk does not reset the array by default. $fruits = array ("d"=>"lemon", "a"=>"orange", "b"=>"banana", "c"=>"apple"); function test_alter (&$item1, $key, $prefix) { $item1 = "$prefix: $item1"; } function test_print ($item2, $key) { echo "$key. $item2<br>\n"; } array_walk ($fruits, 'test_print'); reset ($fruits); array_walk ($fruits, 'test_alter', 'fruit'); reset ($fruits); array_walk ($fruits, 'test_print'); See also each and list. arsort Sort an array in reverse order and maintain index association void arsort array array int sort_flags 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); reset ($fruits); while (list ($key, $val) = each ($fruits)) { echo "$key = $val\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. You may modify the behavior of the sort using the optional parameter sort_flags, for details see sort. See also: asort, rsort, ksort, and sort. asort Sort an array and maintain index association void asort array array int sort_flags 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); reset ($fruits); while (list ($key, $val) = each ($fruits)) { echo "$key = $val\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. You may modify the behavior of the sort using the optional parameter sort_flags, for details see sort. See also arsort, rsort, ksort, and sort. compact Create array containing variables and their values array compact mixed varname mixed ... Compact takes a variable number of parameters. Each parameter can be either a string containing the name of the variable, or an array of variable names. The array can contain other arrays of variable names inside it; compact handles it recursively. For each of these, compact looks for a variable with that name in the current symbol table and adds it to the output array such that the variable name becomes the key and the contents of the variable become the value for that key. In short, it does the opposite of extract. It returns the output array with all the variables added to it. Any strings that are not set will simply be skipped. $city = "San Francisco"; $state = "CA"; $event = "SIGGRAPH"; $location_vars = array ("city", "state"); $result = compact ("event", "nothing_here", $location_vars); After this, $result will be array ("event" => "SIGGRAPH", "city" => "San Francisco", "state" => "CA"). See also extract. 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. $a[0] = 1; $a[1] = 3; $a[2] = 5; $result = count ($a); //$result == 3 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", "egon", "marliese"); $bar = each ($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, $HTTP_POST_VARS: echo "Values submitted via POST method:<br>"; reset ($HTTP_POST_VARS); 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 mixed end array array End advances array's internal pointer to the last element, and returns that element. See also: current, each, end, next, and reset. extract Import variables into the symbol table from an array int extract array var_array int extract_type string prefix This function is used to import variables from an array into the current symbol table. It takes associative array var_array and treats keys as variable names and values as variable values. For each key/value pair it will create a variable in the current symbol table, subject to extract_type and prefix parameters. Since version 4.0.5 this function returns the number of variables extracted. extract checks each key to see whether if constitutes a valid variable name and also for collisions with existing variables in the symbol table. The way invalid/numeric keys and collisions are treated is determined by extract_type. It can be one of the following values: EXTR_OVERWRITE If there is a collision, overwrite the existing variable. EXTR_SKIP If there is a collision, don't overwrite the existing variable. EXTR_PREFIX_SAME If there is a collision, prefix the variable name with prefix. EXTR_PREFIX_ALL Prefix all variable names with prefix. Since PHP 4.0.5 this includes numeric ones as well. EXTR_PREFIX_INVALID Only prefix invalid/numeric variable names with prefix. This flag has been added in PHP 4.0.5. If extract_type is not specified, it is assumed to be EXTR_OVERWRITE. Note that prefix is only required if extract_type is EXTR_PREFIX_SAME, EXTR_PREFIX_ALL, or EXTR_PREFIX_INVALID. If the prefixed result is not a valid variable name, it is not imported into the symbol table. extract returns the number of variables successfully imported into the symbol table. A possible use for extract is to import into symbol table variables contained in an associative array returned by wddx_deserialize. <?php /* Suppose that $var_array is an array returned from wddx_deserialize */ $size = "large"; $var_array = array ("color" => "blue", "size" => "medium", "shape" => "sphere"); extract ($var_array, EXTR_PREFIX_SAME, "wddx"); print "$color, $size, $shape, $wddx_size\n"; ?> The above example will produce: blue, large, sphere, medium The $size wasn't overwritten, becaus we specified EXTR_PREFIX_SAME, which resulted in $wddx_size being created. If EXTR_SKIP was specified, then $wddx_size wouldn't even have been created. EXTR_OVERWRITE would have cause $size to have value "medium", and EXTR_PREFIX_ALL would result in new variables being named $wddx_color, $wddx_size, and $wddx_shape. You must use an associative array, a numerically indexed array will not produce results. See also: compact. in_array Return TRUE if a value exists in an array bool in_array mixed needle array haystack bool strict Searches haystack for needle and returns TRUE if it is found in the array, FALSE otherwise. If the third parameter strict is set to TRUE then the in_array will also check the types of the needle in the haystack. $os = array ("Mac", "NT", "Irix", "Linux"); if (in_array ("Irix", $os)){ print "Got Irix"; } // This will output: 1.13 found with strict check See also array_search. array_search Searches the array for a given value and returns the corresponding key if successful mixed array_search mixed needle array haystack bool strict Searches haystack for needle and returns the key if it is found in the array, FALSE otherwise. If the third parameter strict is set to TRUE then the array_search will also check the types of the needle in the haystack. See also in_array. 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 and next. krsort Sort an array by key in reverse order int krsort array array int sort_flags Sorts an array by key in reverse order, maintaining key to data correlations. This is useful mainly for associative arrays. $fruits = array ("d"=>"lemon", "a"=>"orange", "b"=>"banana", "c"=>"apple"); krsort ($fruits); reset ($fruits); while (list ($key, $val) = each ($fruits)) { echo "$key -> $val\n"; } This example would display: fruits[d] = lemon fruits[c] = apple fruits[b] = banana fruits[a] = orange You may modify the behavior of the sort using the optional parameter sort_flags, for details see sort. See also asort, arsort, ksort sort, natsortand rsort. ksort Sort an array by key int ksort array array int sort_flags 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); reset ($fruits); while (list ($key, $val) = each ($fruits)) { echo "$key -> $val\n"; } This example would display: fruits[a] = orange fruits[b] = banana fruits[c] = apple fruits[d] = lemon You may modify the behavior of the sort using the optional parameter sort_flags, for details see sort. See also asort, arsort, sort, natsort, and rsort. The second parameter was added in PHP 4. 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 $result = mysql_query ($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 and array. natsort Sort an array using a "natural order" algorithm void natsort array array This function implements a sort algorithm that orders alphanumeric strings in the way a human being would. This is described as a "natural ordering". An example of the difference between this algorithm and the regular computer string sorting algorithms (used in sort) can be seen below: $array1 = $array2 = array ("img12.png","img10.png","img2.png","img1.png"); sort($array1); echo "Standard sorting\n"; print_r($array1); natsort($array2); echo "\nNatural order sorting\n"; print_r($array2); The code above will generate the following output: Standard sorting Array ( [0] => img1.png [1] => img10.png [2] => img12.png [3] => img2.png ) Natural order sorting Array ( [3] => img1.png [2] => img2.png [1] => img10.png [0] => img12.png ) For more infomation see: Martin Pool's Natural Order String Comparison page. See also natcasesort, strnatcmp and strnatcasecmp. natcasesort Sort an array using a case insensitive "natural order" algorithm void natcasesort array array This function implements a sort algorithm that orders alphanumeric strings in the way a human being would. This is described as a "natural ordering". natcasesort is a case insensitive version of natsort. See natsort for an example of the difference between this algorithm and the regular computer string sorting algorithms. For more infomation see: Martin Pool's Natural Order String Comparison page. See also sort, natsort, strnatcmp and strnatcasecmp. 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, or elements that have a key value of 0 then this function will return FALSE for these elements as well. To properly traverse an array which may contain empty elements or elements with key values of 0 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, and prev. rsort Sort an array in reverse order void rsort array array int sort_flags This function sorts an array in reverse order (highest to lowest). $fruits = array ("lemon", "orange", "banana", "apple"); rsort ($fruits); reset ($fruits); while (list ($key, $val) = each ($fruits)) { echo "$key -> $val\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. You may modify the behavior of the sort using the optional parameter sort_flags, for details see sort. 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. You must use srand to seed this function. $numbers = range (1,20); srand ((double)microtime()*1000000); shuffle ($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 int sort_flags This function sorts an array. Elements will be arranged from lowest to highest when this function has completed. <?php $fruits = array ("lemon", "orange", "banana", "apple"); sort ($fruits); reset ($fruits); while (list ($key, $val) = each ($fruits)) { echo "fruits[".$key."] = ".$val; } ?> This example would display: fruits[0] = apple fruits[1] = banana fruits[2] = lemon fruits[3] = orange The fruits have been sorted in alphabetical order. The optional second parameter sort_flags may be used to modify the sorting behavior using theese valies: Sorting type flags: SORT_REGULAR - compare items normally SORT_NUMERIC - compare items numerically SORT_STRING - compare items as strings See also: arsort, asort, ksort, natsort, natcasesort, rsort, usort, array_multisort, and uksort. The second parameter was added in PHP 4. 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. Please see usort and uksort for examples of user-defined comparison functions. See also: usort, uksort, sort, asort, arsort, ksort and rsort. 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 cmp ($a, $b) { if ($a == $b) return 0; return ($a > $b) ? -1 : 1; } $a = array (4 => "four", 3 => "three", 20 => "twenty", 10 => "ten"); uksort ($a, "cmp"); while (list ($key, $value) = each ($a)) { echo "$key: $value\n"; } This example would display: 20: twenty 10: ten 4: four 3: three See also: usort, uasort, sort, asort, arsort, ksort, natsort and rsort. usort Sort an array by values using a user-defined comparison function void usort array array string cmp_function This function will sort an array by its values using a user-supplied comparison function. If the array you wish to sort needs to be sorted by some non-trivial criteria, you should use this function. The comparison function must return an integer less than, equal to, or greater than zero if the first argument is considered to be respectively less than, equal to, or greater than the second. If two members compare as equal, their order in the sorted array is undefined. function cmp ($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: $value\n"; } This example would display: 0: 6 1: 5 2: 3 3: 2 4: 1 Obviously in this trivial case the rsort function would be more appropriate. function cmp ($a, $b) { return strcmp($a["fruit"],$b["fruit"]); } $fruits[0]["fruit"] = "lemons"; $fruits[1]["fruit"] = "apples"; $fruits[2]["fruit"] = "grapes"; usort($fruits, "cmp"); while (list ($key, $value) = each ($fruits)) { echo "\$fruits[$key]: " . $value["fruit"] . "\n"; } When sorting a multi-dimensional array, $a and $b contain references to the first index of the array. This example would display: $fruits[0]: apples $fruits[1]: grapes $fruits[2]: lemons 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: uasort, uksort, sort, asort, arsort,ksort, natsort, and rsort.