array_combine, but how about the key array has the same values?

[blackhorse]

//this question is about array_merge

$array1=array(1, 2, 1);
$array2=array(1, 2, 3, 4);

$array3=array_merge($array1, $array2);

print_r ($array3);  //result is Array ( [0] => 1 [1] => 2 [2] => 1 [3] => 1 [4] => 2 [5] => 3 [6] => 4 ) 

//but the merge I want is if the same key, the value added up as the new value and still use the same key, if the key in array2 but not in array1, then append to array1.	
//meaning: I want the result to be Array ( [0] => 2 [1] => 4 [2] => 4 [3] => 4 )
//so here is my function

$array1_keys=array_keys($array1);
for ($index=0; $index<count($array1); $index++)
{
	$this_key=$array1_keys[$index];
	$this_value=$array1[$index];

	$array4[$this_key]+=$this_value;
}

$array2_keys=array_keys($array2);
for ($index=0; $index<count($array2); $index++)
{
	$this_key=$array2_keys[$index];
	$this_value=$array2[$index];

	$array4[$this_key]+=$this_value;
}

print_r ($array4)  //result is Array ( [0] => 2 [1] => 4 [2] => 4 [3] => 4 ) as I want.
				   // my question: is this the simple and right way to achienve what I want?

[blackhorse]

//this question is about array_combine (php5)

$array1=array(1, 2, 1); //it has the same value as 1 will be used as key
$array2=array(1, 2, 3); //value 1 will be assign to key 1, and value 3 will be assigned to key 1 again and overwrite the previous value?

$array3=array_combine($array1, $array2);

print_r ($array3); //what will be $array3? i don't have php5 yet.
//will $array3 be Array ( [1] => 3 [2] => 2 )

//but if I want sum up the values of array 2, if the key from array 1 is the same.

//meaning, the value 1 and 3 will be added up and assigned to key 1 in the merge
//so I have to use the following function

for ($index=0; $index<count($array1); $index++)
{
	$this_key=$array1[$index];
	$this_value=$array2[$index];

	$array4[$this_key]+=$this_value;
}

print_r ($array4)  //the return is Array ( [1] => 4 [2] => 2 ), it is the array I want.

                                         //is this the right way to achieve what I want from "combine" arrays?  Thanks!

[NogDog]

I merged these two threads together, as I assume they have to do with the same thing?

[blackhorse]

Well. actually they are not the same thing. 🙂 I was looking for where is my first thread.

the first thread was about merge two arrays together.

The second thread was about combine two arrays use one array as keys and use another array as values.

But I am using the similiar approach to solve these two different issues. I just wanted to see if my approach is right, simple or efficient, or there are better ones.

So combine them is fine for me.

Thanks!