如何从数组中提取字符串然后检查它的第一个字母？

  puts "Please Enter First Initial..."
  initial = gets
  first_letter( name, age, initial)  

  def first_letter( x, y, z)
       index = 0
       while index < x.length
        --->if z == (x[index])
        puts "#{x[index]}   #{y[index]}"
        end
        index += 1
      end
    end
  puts "Please Enter First Initial..."
  initia