substring?

substring.rb

def substring?(s1, s2)
        a = s1.size
        b = s2.size

        i = 0
        while i <= a
                x = i
                j = 0
                while j <= b
                        return true if j == b
                        return false if x == a
                        break if s1[x] != s2[j]
                        x += 1
                        j += 1
                end
                i += 1
        end
end