php: the best practice to pass two global arrays to the function to modify them

Question

There are two arrays that need to be changed within a function. How to pass that arrays? The way I know is to declare 2 arrays as global variables within a function:

function myfunc(){
 global $arr1;
 global $arr2;
 //do something
}

Does it make sense and is it possible to pass two arrays as references instead? How (in case if Yes)?

Answer 1

Yes, you can pass the arrays as reference, and that would be preferable to using globals.

function myfunc( array &$arr1, array &$arr2 ) {
    // do something
}

myfunc( $someArray, $someOtherArray );

The & in the function definition tells PHP to pass a reference rather than a value.

Answer 2

Here is how you can pass them by reference, define your function as follows:

function myfunc(&$arr1, &$arr2) {
    // ... modify arrays here
}

Just prepend the function arguments you want passed by reference with an & . Now when they are received by the function, they are references.

You do not have to (and should not) put the & in front of the variables when you are calling the function as this results in a call-time pass-by-reference notice. Just pass them to your function as usual $res = myfunc($first, $second);

See Passing by Reference

Answer 3

I would take another approach (if the arrays are not too big...) to make it clear where the function is called that the original arrays will be changed (although I probably would never changed two global arrays in one function...):

function call:

list($array1, $array2) = myfunc($array1, $array2);

function:

function myfunc($array_x, $array_y){
  //do something
  return array($array_x, $array_y);
}