Question

How can I add new item to array? For example into middle of an array ?Should we use array splice or an array merge ?
Could you explain me the difference between both function ?

Say I have

$a1=array("a"=>"Horse","b"=>"Dog","c"=>"Cow",);
$a2=array("d"=>"Cat");

Now I need to add $a2 in 2 position .

Which one should I use ?

Answer 1

You can use array_splice, except that won’t keep your keys.

$a1 = array("a"=>"Horse", "b"=>"Dog", "c"=>"Cow");
$a2 = array("d"=>"Cat");

array_splice($a1, 2, 0, $a2);

// $a1 is now: array("a"=>"Horse", "b"=>"Dog", 0=>"Cat", "c"=>"Cow");

If you want Cat to have a key of d, you can use a mix of array_slice and the array union operator (+):

$a1 = array_slice($a1, 0, 2) + $a2 + array_slice($a1, 2);

// $a1 is now: array("a"=>"Horse", "b"=>"Dog", "d"=>"Cat", "c"=>"Cow");