Substring algorithm

Question

Can someone explain to me how to solve the substring problem iteratively?

The problem: given two strings S=S₁S₂S

Answer 1

Here is my PHP variation that includes a check to make sure the Needle does not exceed the Haystacks length during the search.

= $len) { return false; }
                                if($needle[$j] != $haystack[$i+$j]) {
                                        $found = false;
                                        continue;
                                }
                        }
                        if($found) {
                                echo " . . . . . . SUCCESS!!!! startPos: $i\n";
                                return true;
                        }
                }
        }
        echo " . . . . . . FAILURE!\n" ;
        return false;
}

assert(substring("haystack","hay"));
assert(!substring("ack","hoy"));
assert(substring("hayhayhay","hayhay"));
assert(substring("mucho22","22"));
assert(!substring("str","string"));
?>

Left in some echo's. Remove if they offend you!