PHP MySQL - Stilson.net

www.it-ebooks.infoCHAPTER 5 • ARRAYSRetrieving Array KeysThe array_keys() function returns an array consisting of all keys located in an array. Its prototypefollows:array array_keys(array array [, mixed search_value [, boolean preserve_keys]])If the optional search_value parameter is included, only keys matching that value will be returned.The following example outputs all of the key values found in the $state array:$state["Delaware"] = "December 7, 1787";$state["Pennsylvania"] = "December 12, 1787";$state["New Jersey"] = "December 18, 1787";$keys = array_keys($state);print_r($keys);The output follows:Array ( [0] => Delaware [1] => Pennsylvania [2] => New Jersey )Setting the optional preserve_keys parameter (introduced in PHP 5.0.2) to true will cause the arrayvalues’ keys to be preserved in the returned array.Retrieving Array ValuesThe array_values() function returns all values located in an array, automatically providing numericindexes for the returned array. Its prototype follows:array array_values(array array)The following example will retrieve the population numbers for all of the states found in$population:$population = array("Ohio" => "11,421,267", "Iowa" => "2,936,760");print_r(array_values($population));This example will output the following:Array ( [0] => 11,421,267 [1] => 2,936,760 )Traversing ArraysThe need to travel across an array and retrieve various keys, values, or both is common, so it’s not asurprise that PHP offers numerous functions suited to this need. Many of these functions do double113