gistfile1.rb

class String

  def strstr(pattern)
    0.upto self.size do |i|
      matches = 0
      0.upto pattern.size do |j|
        if self[i + j] == pattern[j]
          matches += 1
        else
          break
        end
        return i if matches == pattern.size
      end
    end

    -1
  end
end

puts "hello".strstr("el")
puts "hello".strstr("ll")
puts "hello".strstr("o!")
puts "hello".strstr("y")
puts "hello".strstr("hello")
puts "hello".strstr("x")
puts "hello".strstr(" ")
puts "hello".strstr("lo")