function that returns the string representation of the sum of those integers

sumStrings.php

<?php
function sumStrings($string1,$string2) {
    $result = (int) $string1 + (int) $string2;
    return (string) $result;
}

/*
* input: $string1 = "1", $string2 = "2"
*/

/*
* output: "3"
*/