map函数

• 将 列表里的数字平方

  num_1 = [2,5,68,4,9]
  num_0 = []
  for i in num_1 :
      num_0 .append(i**2)
  print(num_0 )

  def map_test(arry):
      num_0 = []
      for i in num_1:
          num_0.append(i ** 2)
      return num_0
  print(map_test(num_1 ))

  msg = "shuai"
  print(list(map(lambda x:x.upper(),msg) ))