在python中，要判断特定的值是否存在列表中，可使用关键字in,判断特定的值不存在列表中，可使用关键字not in

letters = ['A','B','C','D','E','F','G']if 'A' in letters:    print('A'+' exists')if 'h' not in letters:    print('h'+' not exists')

打印结果：

A exists

h not exists

一个稍微复杂的案例

定义2个列表分别为list_01跟list_02

list_01 = ['A','B','C','H'] list_02 = ['A','B','E','F']

通过判断查看list_01在list_02中的存在情况

list_01 = ['A','B','C','H']list_02 = ['A','B','E','F']for letter in list_01:    if letter in list_02:        print(letter+' is exists')    else:        print(letter+' is not exists')

打印结果：

A is exists

B is exists

C is not exists

H is not exists