Question

I have E-20-99 in a string i want to get last value 99 and add 1 means 100 and then wants to generate new string E-20-100.

Answer 1

If your string ALWAYS looks like this, you can easily break it without a regex, simply by using explode()

$string = "E-20-99";
$parts = explode('-', $string);

$last_part = $parts[2] + 1;
$parts[2] = $last_part;

$string = implode('-', $parts);

echo $string;