python - 我想在代码上有一个 'else' 语句，使用 'for' 和 'if' 语句迭代列表以查找作为字典键的项目

Question

我使用“for”语句，然后使用“if”语句从字典中的列表中查找项目。我希望“好奇，告诉我更多”只打印一次。

以下是我期望该程序的工作方式:

input: i have a cat
output: Cats are the greatest animals in the world

Input:i do not like dogs 
Output: Dogs are boring

input:i love my pet
Output:Curious, tell me more

我当前的代码:

Dict_1 = {'cat':'Cats are the greatest animals in the world','dog':'Dogs are boring'}
query = 0
while (not query=='quit'):
     query = input().split()
     for i in query:
          if i in Dict_1:
               query = Dict_1[i]
               print(query)
          else:
               print('Curious, tell me more')

Answer 1

与 query = input().split() ，你正在转向query到一个列表中。例如。如果用户输入 cat dog ，查询将是 ['cat','dog'] .

所以，不要检查 query=='quit' (这永远不会是真的，因为 query 是一个列表而不是字符串)，您应该检查查询是否包含 'quit'与 'quit' in query .

如果您不想打印'Curious, tell me more'当用户退出时，则使用无限 while循环，并在 'quit' 时中断循环已读。

您可以使用集合交集生成包含在查询中找到的命令的集合:commands_found = set(Dict_1.keys()) & set(query)

这是一个有效的实现:

Dict_1 = {'cat':'Cats are the greatest animals in the world','dog':'Dogs are boring'}
query = []
while True:
    query = input().split()
    if 'quit' in query:
        break
    commands_found = set(Dict_1.keys()) & set(query)
    if commands_found:
        for i in commands_found: print(Dict_1[i])
    else:
        print('Curious, tell me more')

请注意，我正在初始化 query现在作为列表 query = [] 。输出:

I like my cat
Cats are the greatest animals in the world
I like my cat and dog
Cats are the greatest animals in the world
Dogs are boring
I like my racoon
Curious, tell me more
I want to quit