How to put comma separated string in two different arrays?

This should work for you:

First explode() your string by a comma. Then you can array_filter() the numbers out. And at the end you can simply take the array_diff() from the $arr and the $numbers array.

<?php

    $str = "1,First,2,Second,3,Third,4,Forth,5,Fifth";
    $arr = explode(",", $str);

    $numbers = array_filter($arr, "intval"); 
    $text = array_diff($arr, $numbers);

?>

You can use explode() and array_map() over the results:

$str = '1,First,2,Second,3,Third,4,Forth,5,Fifth';

array_map(function($item) use (&$numbers, &$strings) {
    if(is_numeric($item)) {
        $numbers []= $item;
    } else {
        $strings []= $item;
    }
}, explode(',', $str));

var_dump($numbers, $strings);

<?php

$str = array(1,'First',2,'Second',3,'Third',4,'Forth',5,'Fifth');

$letters =array();
$no = array();

for($i=0;$i<count($str);$i++){
  if($i%2 ==0){
    $letters[] = $str[$i];

  }else{
    $no[] = $str[$i];
  }
}
  print_r($no);
  print_r($letters);
?>

May be this can help you

$str = '1,First,2,Second,3,Third,4,Forth,5,Fifth';

$array = explode(',',$str);

$number = array();
$string = array();


foreach($array as $val)
{
    if(is_numeric($val))
    {
        $number[] = $val;
    }
    elseif(!is_numeric($val))
    {
        $string[] = $val;
    }
}

echo $commNum = implode(',',$number); // These are strings
echo '<br/>'.$commStr = implode(',',$string); // These are strings

echo '<pre>';
print_r($number);  // These are arrays

echo '<pre>';
print_r($string);  // These are arrays

This should work for you.

$str = '1,First,2,Second,3,Third,4,Forth,5,Fifth';
$result = explode(',',$str);
$number = array();
$text = array();
foreach(explode(',',$str) as $key => $value){
    if($key % 2 == 1){
        $text[] = $value;
    }elseif($key % 2 == 0){
        $number[] = $value;
    }
}
print_r($number);//Array ( [0] => 1 [1] => 2 [2] => 3 [3] => 4 [4] => 5 )
print_r($text);//Array ( [0] => First [1] => Second [2] => Third [3] => Forth [4] => Fifth )

and if your array is not consistent in this manner then some of these above answers are well suited for you like of Rizier123,hek2mgl,& Sunil's one

I'm updating my answer for your correspondent comments over Adrian

foreach(explode(',',$str) as $key => $value){
        if(is_numeric($value)){
            $number[] = $value;
        }else{
            $text[] = $value;
        }
    }

You can use explode, but you need apply some filter in this case is is_numeric:

<?php

$str = '1,First,2,Second,3,Third,4,Forth,5,Fifth, erewwrw , 6 ';

$array = explode(',', $str);

$array_numbers = array();
$array_letters = array();

for($i = 0; $i < count($array); $i++) {
    if(is_numeric(trim($array[$i]))) {
      $array_numbers[] = trim($array[$i]);  
    } else {
      $array_letters[] = trim($array[$i]);
    }       
}
print_r($array_numbers);
print_r($array_letters);

?>

Output:

Array
(
    [0] => 1
    [1] => 2
    [2] => 3
    [3] => 4
    [4] => 5
)
Array
(
    [0] => First
    [1] => Second
    [2] => Third
    [3] => Forth
    [4] => Fifth
)

Assuming that your string contains number followed by string and so on,

following should be the solution.

Create two blank arrays: $numbers and $strings.

Just loop over the array and get even and odd elements.

Even elements should go to numbers array and odd elements should go to strings array.

$str = '1,First,2,Second,3,Third,4,Forth,5,Fifth';
$numbers = array();
$strings = array();
$temp = explode(',', $str);
$i=0;
foreach ($temp as $e) {
    if ($i%2) {
        $strings[] = $e;
    }
    else {
        $numbers[] = $e;
    }
    ++$i;
}

echo '<pre>';
print_r($numbers);
echo '</pre>';

echo '<pre>';
print_r($strings);
echo '</pre>';