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array_keys

array_keys -- Return all the keys of an array

Description

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.

Example 1. array_keys() example

  1 
  2 $array = array(0 => 100, "color" => "red");
  3 array_keys ($array);       // returns array (0, "color")
  4 
  5 $array = array(1, 100, 2, 100);
  6 array_keys ($array, 100);  //  returns array (0, 2) 
  7 

See also array_values().

Note: This function was added in PHP 4.0.

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