How to save only numeric numbers from string into an array of int in PHP

Question

in my POST variable i have: print_r($_POST["partecipanti"]); It displays ["1", "2"]

I want to save only the numbers of the post variable in an int array. I tried

$array = array();
 preg_match_all('/-?\d+(?:\.\d+)?+/', $_POST["partecipanti"], $array);

But print_r($array) returns

Array (
 [0] => Array (
        [0] => 1
        [1] => 2
        )
    )

How can i have a variable like

Array (
  [0] => 1
  [1] => 2
     )

Hope i explained good, thanks all in advance

There is no difference between a string with only number and an integer in php. But if you must, you can use intval() to convert to integer. — Andreas
– Andreas, Commented Jun 9, 2018 at 8:57
@Andreas of course yes there is a difference between numeric string and integer in php. Try is_int("1") it returns false. — WizardNx
– WizardNx, Commented Jun 9, 2018 at 9:06
print_r($array[0]) And I suppose $_POST["partecipanti"] is a json string and can be decoded. — u_mulder
– u_mulder, Commented Jun 9, 2018 at 9:21
@WizardNx not sure what you are trying to say. $_POST is always in string format. Using is_int() on a obvious string is quite meaningless. — Andreas
– Andreas, Commented Jun 9, 2018 at 11:15
@Andreas it's actually meaningless yes, but you were saying "there is no difference between a string with only number and an integer in php" which is wrong or like I would like to say: "as true as is_int("1")". — WizardNx
– WizardNx, Commented Jun 9, 2018 at 11:34

Tewdyn · Accepted Answer · 2018-06-09 09:04:17Z

1

preg_match_all returns a new multidimensional array every time. But you could just "pop" the array:

$array = array();
preg_match_all('/-?\d+(?:\.\d+)?+/', $_POST["partecipanti"], $array);
$array = $array[0];

Returns:

Array (
  [0] => 1
  [1] => 2
)

answered Jun 9, 2018 at 9:04

Tewdyn

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1 Comment

WizardNx Over a year ago

Note that there is no need to declare $array before the preg_match_all.

xanadev · Accepted Answer · 2018-06-09 09:28:00Z

0

to filter integer values from an array, use array_filter

$arr = array_filter($_POST["participanti"], function($v) { return is_int($v); });

In case you want to convert the array values into integers:

$arr = array_map(function($v) { return (int)$v; }, $_POST["participanti"]);

In both cases the $arr contains only integer values.

edited Jun 9, 2018 at 9:28

answered Jun 9, 2018 at 9:10

xanadev

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2 Comments

xanadev Over a year ago

i'm sure he was asking for a way to get only integer values from the array. not convert the array values into integers. it's filtering not converting, converting would need a different approach.

xanadev Over a year ago

edited the answer to cover filtering as well as converting.

The fourth bird · Accepted Answer · 2018-06-09 13:04:54Z

Assuming $_POST["partecipanti"]) is a string because you use it directly in your example and the second parameter of preg_match_all is a string.

preg_match_all returns an array where the matches are in the first entry and contains array of strings. You could get that array by using $array[0] .

Besides 1 and 2, your regex -?\d+(?:\.\d+)?+ also matches for example -8.44 or 99999999999999999999999999.

If you want an array of int, you could use array_map with for example the function intval for the callback.

Note the maximum size of an int and the rounding of the values.

For example:

$str = "test 1, test 2, test 2.3 and -8.44 plus 99999999999999999999999999999999999999999999999999";
preg_match_all('/-?\d+(?:\.\d+)?/', $str, $array);
$array = array_map/**/("intval", $array[0]);
var_dump($array);

Demo

That results in:

array(5) {
  [0]=>
  int(1)
  [1]=>
  int(2)
  [2]=>
  int(2)
  [3]=>
  int(-8)
  [4]=>
  int(9223372036854775807)
}

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