python之当单词不在句子中时无法让程序打印 "not in sentence"

我有一个程序要求输入一个句子，然后要求输入一个词，并告诉你那个词的位置:

sentence = input("enter sentence: ").lower() 
askedword = input("enter word to locate position: ").lower() 
words = sentence.split(" ") 
 
for i, word in enumerate(words): 
     if askedword == word : 
          print(i+1) 
    #elif keyword != words : 
         #print ("this not") 

但是，当我编辑程序时，如果输入的单词不在句子中，则打印“this isn't in the sentence”，我无法让程序正常工作

请您参考如下方法:

列表是序列，因此您可以使用 the in operation在它们上测试 words 列表中的成员资格。如果在里面，用words.index找到句子里面的位置:

sentence = input("enter sentence: ").lower() 
askedword = input("enter word to locate position: ").lower() 
words = sentence.split(" ") 
 
if askedword in words: 
    print('Position of word: ', words.index(askedword)) 
else: 
    print("Word is not in the given sentence.") 

带有示例输入:

enter sentence: hello world 
 
enter word to locate position: world 
Position of word: 1 

并且，一个错误的案例:

enter sentence: hello world 
 
enter word to locate position: worldz 
Word is not in the given sentence. 

如果您要检查多个匹配项，那么使用 enumerate 的列表理解是可行的方法:

r = [i for i, j in enumerate(words, start=1) if j == askedword] 

然后检查列表是否为空并相应地打印:

if r: 
    print("Positions of word:", *r) 
else: 
    print("Word is not in the given sentence.")