我需要停止我的for循环，但休息不会工作

Question

我已经写了一些代码，可以找到用户在一个句子中输入的单词的位置。但是，在他们输入词语后，我需要找到该位置的代码并打印出来，然后停在那里。但它不会停止，而是继续到else语句，如果他们输入不在句子中的单词，会发生什么情况。如果我使用break，它只会打印单词的第一个位置，如果它在句子中出现多次。我该怎么办？

sentence = "ask not what your country can do for you ask what you can do for your country" 
print(sentence) 
keyword = input("Input a keyword from the sentence: ").lower() 
words = sentence.split(' ') 

for i, word in enumerate(words): 
    if keyword == word: 
     print("The position of %s in the sentence is %s" % (keyword,i+1)) 


if keyword != word: 
    keyword2 = input("That was an invalid input. Please enter a word that is in the sentence: ").lower() 
    words = sentence.split(' ') 
    for i, word in enumerate(words): 
     if keyword2 == word: 
      print("The position of %s is %s" % (keyword2,i+1)) 

Answer 1

您可以先获取所有索引，然后只在没有匹配索引时才执行第二个函数。

indexes = [i for i, word in enumerate(words) if word == keyword] 
if indexes: 
    for i in indexes: 
     print('The position is {}'.format(i)) 

if not indexes: 
    ... 

你也可以使用一个while循环，这样就可以只使用一个单一的步骤。

keyword = input("Please enter a word that is in the sentence: ").lower() 
indexes = [i for i, word in enumerate(words) if word == keyword] 
while not indexes: 
    keyword = input("That was an invalid input. Please enter a word that is in the sentence: ").lower() 
    indexes = [i for i, word in enumerate(words) if word == keyword] 

for i in indexes: 
    print('The position is {}'.format(i))