php - create,dynamically, an array initialized with N null elements

Question

I want to create dynamically an array with N (without knowking N) elements.

Something like a function

public function create_array($num_elements){

     .....
}

that return me something like

//call the function.... 
create_array(3);

//and the output is: 
array{
   0 => null
   1 => null
   2 => null
}

I've already thought about array_fill and a simple foreach loop.

Are there any other solutions?

do yourself and everyone else a favour and just use array_fill — xzyfer
– xzyfer, Commented Jul 18, 2011 at 8:56
array_fill is a core function - nothing will be faster than that. What would you expect from the "best solution"? — Stefan Gehrig
– Stefan Gehrig, Commented Jul 18, 2011 at 9:18
The solution which works best. If array_fill is the function which works faster and easiest, probably it's the best solution (personal opinion). — alesdario
– alesdario, Commented Jul 18, 2011 at 10:44

Stefan Gehrig · Accepted Answer · 2011-07-18 08:48:12Z

50

Actually a call to array_fill should be sufficient:

//...
public function create_array($num_elements){
    return array_fill(0, $num_elements, null);
}
//..

var_dump(create_array(3));
/*
array(3) {
  [0]=> NULL
  [1]=> NULL
  [2]=> NULL
}
*/

answered Jul 18, 2011 at 8:48

Stefan Gehrig

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Comments

Dan Grossman · Accepted Answer · 2011-07-18 08:47:58Z

3

for ($i = 0; $i < $num_elements; $i++) {
    $array[$i] = null;
}

answered Jul 18, 2011 at 8:47

Dan Grossman

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1 Comment

Melsi Over a year ago

this is the most obvious solution, and the best (for my test) since the other solutions are not faster than this!

Iharob Al Asimi · Accepted Answer · 2015-11-08 12:16:36Z

1

array_fill(0, $element, null);

using this php function, you can create array with starting index 0, and all will have null value.

edited Nov 8, 2015 at 12:16

Iharob Al Asimi

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answered Jul 18, 2011 at 8:53

Rukmi Patel

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Comments

Ondrej Slinták · Accepted Answer · 2011-07-18 08:51:31Z

0

Simple use of array_fill sounds like the easiest solution:

$arr = array_fill($start_at, $num_elements, null);

answered Jul 18, 2011 at 8:51

Ondrej Slinták

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Comments

Delan Azabani · Accepted Answer · 2011-07-18 09:00:12Z

0

Do array_fill and foreach not work?

Of course, the simplest solution that comes to mind is

function create_array($num_elements) {
    $r = array();
    for ($i = 0; $i < $num_elements; $i++)
        $r[] = null;
    return $r;
}

array_fill should also work:

function create_array($num_elements) {
    return array_fill(0, $num_elements, null);
}

edited Jul 18, 2011 at 9:00

answered Jul 18, 2011 at 8:48

Delan Azabani

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Comments

Roman Kucher · Accepted Answer · 2019-07-07 22:00:07Z

0

In foreach loop you can simply use range()

answered Jul 7, 2019 at 22:00

Roman Kucher

11

1 Comment

Benjamin H Boruff Over a year ago

Unfortunately, range doesn't give us a way to set a default value like array_fill does. Close, though!

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