String to array of Integers php

Question

I wan to convert a string for example 1,2,3,4,5,6 to an array of integers in php? I find functions that only have access to the first character of the string for example 1. How can I conert the whole string to array?

function read_id_txt()
{

        $handle_file = fopen("temporalfile.txt", 'r'); 

        $i=0;

        while ($array_var[$i] = fgets($handle_file, 4096)) { 
            echo "<br>";
            print_r($array_var[i]);
            $i++;
        }

        fclose($handle_file);   

        $temp=explode(" ", $array_var[0]);      

        return $temp;   


}

Solution 1

Use PHP's explode.

$str = "1,2,3,4,5,6";
$arr = explode("," $str); // array( '1', '2', '3', '4', '5', '6' );

foreach ($arr AS $index => $value)
    $arr[$index] = (int)$value; 

// casts each value to integer type -- array( 1, 2, 3, 4, 5, 6 );

As suggested by Tim Cooper, using array_walk is simpler than the above loop:

array_walk($arr, 'intval');

Solution 2

return array_map('intval', explode(",", '1,2,3,4,5,6,7,8,9'));

Solution 3

The above answers could potentially return non-numeric values

array_walk & array_map with intval

Both return arrays that are tainted with non-numeric values.

$string = ',g,6,4,3,f,32,a,';
$array = explode(',', $string);
array_walk($array, 'intval');
$arrayMap = array_map('intval', $array);
var_dump($array);
var_dump($arrayMap);
/*
     array(9) {
      [0]=>
      string(0) ""
      [1]=>
      string(1) "g"
      [2]=>
      string(1) "6"
      [3]=>
      string(1) "4"
      [4]=>
      string(1) "3"
      [5]=>
      string(1) "f"
      [6]=>
      string(2) "32"
      [7]=>
      string(1) "a"
      [8]=>
      string(0) ""
    }
 */

array_filter to only return numeric values

$string = ',g,6,4,3,f,32,a,';
$array = explode(',', $string);
$numericOnlyArray = array_filter($array,'is_numeric');

var_dump($numericOnlyArray);

/*
    result:
    array(4) {
      [2]=>
      string(1) "6"
      [3]=>
      string(1) "4"
      [4]=>
      string(1) "3"
      [6]=>
      string(2) "32"
    }
*/

To get only integers

$string = ',g,6,4,3,f,32,a,';
$array = explode(',', $string);
$result = array_map('intval', array_filter($array, 'is_numeric'));

var_dump($result);

/*
    result:
    array(4) {
      [2]=>
      int(6)
      [3]=>
      int(4)
      [4]=>
      int(3)
      [6]=>
      int(32)
    }
    }
*/

Solution 4

explode(",",'1,2,3,4,5,6,7,8,9');

http://www.php.net/manual/en/function.explode.php

View more solutions

Comments

[snake plissken]

OK what i ve done is the above $handle_file = fopen("temporalfile.txt", 'r'); $i=0; while ($array_var[$i] = fgets($handle_file, 4096)) { $i++;} fclose($handle_file); $temp=explode(" ", $array_var[0]); print_r($arr); it returns Array ( [0] => 1,2,4,56,6,1,23,34,54,75,43 ) i want to have every value in different cell of the matrix.

[Tim Cooper]

@Josh: That's an array of strings, not integers.

[Tim Cooper]

@Josh: You can simplify that loop with a simple call to array_walk: $arr = array_walk('intval', $arr);.

[Josh]

@Tim Good call! I didn't think of intval (doh!), and thought the loop would be simpler than array_walk because of the necessary function definition.

[snake plissken]

Xm my prob was in exmplode i put the space character instead of ','. With , it works. Thank tou for your time guys.

[TimWolla]

Whilst this may theoretically answer the question, it would be preferable to include the essential parts of the answer here, and provide the link for reference.

[Riesling]

The array_walk thing didn't work for me with php 5.4, but array_map did: $arr = array_map('intval', $arr);

[Josh]

@Riesling Keep in mind, array_map will return a an array, whereas array_walk returns a boolean and modifies the original array. Both should work.

[user2001487]

array_walk returns a bool. This was the only way I could get my string to convert to an array of int to use in Jpgraph.

[Roland Soós]

array_walk makes the modification on the first parameter, so in @josh solution, the $arr variable will contain the integer array not the return value.

[CommandZ]

This will return non-numeric values as well because of the use of intval. "" == 0 using intval

[Ondrej Machulda]

Beware! This wont work i PHP 5.3+! use $arr = array_map('intval', $arr); instead.

[mickmackusa]

No @Josh, array_walk() does NOT modify the original array by default. 3v4l.org/qU4Qo You have to explicitly tell it to modify the elements. This answer is misleading researchers.