PHP Program to split comma delimited string into an array without using library function

<?php
//PHP code to reverse the string without 
//using library function

//function definition 
//it accepts a string and returns an array 
//delimited by commas
function split_string($text){
    //variable to store the result i.e. an array 
    $arr = [];
    //calculate string length
    $strLength = strlen($text);
    $dl = ','; //delimeter
    $j = 0;
    $tmp = ''; //a temp variable
    //logic - it will check all characters
    //and split the string when comma found
    for ($i = 0; $i < $strLength; $i++) {
        if($dl === $text[$i]) {
            $j++;
            $tmp = '';
            continue;
        }
        $tmp .= $text[$i];
        $arr[$j] = $tmp;
    }
    //return the result
    return $arr;
}

//main code i.e. function calling
$str = "New Delhi,Mumbai,Chennai,Banglore";
$result = split_string($str);
echo "string is: " .$str. "<br/>";
echo "arrar of strings after splitting..."."<br/>";
print_r($result);

$str = "Google,Bing,Yahoo!,DuckDuckGo";
$result = split_string($str);
echo "string is: " .$str. "<br/>";
echo "arrar of strings after splitting..."."<br/>";
print_r($result);
?>

Output

string is: New Delhi,Mumbai,Chennai,Banglore
arrar of strings after splitting...
Array
(
    [0] => New Delhi
    [1] => Mumbai
    [2] => Chennai
    [3] => Banglore
)
string is: Google,Bing,Yahoo!,DuckDuckGo
arrar of strings after splitting...
Array
(
    [0] => Google   
    [1] => Bing     
    [2] => Yahoo!   
    [3] => DuckDuckGo
)