replace every second comma of string using php

Question

I have a string of that displays like this:

1235, 3, 1343, 5, 1234, 1

I need to replace every second comma with a semicolon

i.e.

Answer 1

Try this:

$val) {
        if ($counter%2 == 0) {
            $symbol=',';
        }
        else {
            $symbol=';';
        }
        $new_str .= $val.$symbol; 
        $counter++;
    }
    echo $new_str;
    //output::1235, 3; 1343, 5; 1234, 1;
?>