How does PHP index associative arrays? -

as know, in associative arrays, if keys not set, set automatically. seem doesn't make sense in case:

$a = array( '1' => 'one', '3', '2' => 'two'); print_r($a); 

outputs:

array ( [1] => 1 [2] => 2 ) 

so '3'?

within user defined array assigning keys manually array means as

array(1 => 'one',3, 2 => 'two');//[1] => 1 [2] => 3 [2] => 2 

here have two identical index , per docs mentioned last overwrite first

syntax "index => values", separated commas, define index , values. index may of type string or integer. when index omitted, integer index automatically generated, starting @ 0. if index integer, next generated index biggest integer index + 1.

note when 2 identical index defined, last overwrite first.

in order filter case can make changes as

array(1 => 'one',2 =>'two',3) // array ([1] => 1 [2] => 2 [3] => 3) array(3,1 => 'one',2 =>'two') //array ([0] => 3 [1] => 1 [2] => two) array(1 => 'one',2 => 3 ,3 =>'two')// array([1] => 1 [2] => 3 [3] => two) 

docs check parameters