句子中的每个单词是否“有效”

Question

我正在尝试创建一个代码，用户输入一个句子，计算机告诉他们句子中的每个单词是否“有效”（因此在python中，如果他们句子中的每个单词都在“有效单词”列表中）

sentence = input("Please enter a sentence: ")
validwords = ["hello","i","like","python"]
word = sentence.split(" ")
for word in sentence:
      if word in validwords:
           print ("I found a valid word: "+str(word))
      else:
           print ("I found an invalid word: "+str(word))

然而，最后五行似乎不起作用，因为它们将句子中的每个字母而不是每个单词分开。你知道吗

Answer 1

你在循环原句中的字符，而不是你创建的单词列表。试试这个：

sentence = input("Please enter a sentence: ")
validwords = ["hello","i","like","python"]
words = sentence.split(" ")
for word in words:
      if word in validwords:
           print ("I found a valid word: " + word)
      else:
           print ("I found an invalid word: " + word)

Answer 2

你把循环变量搞混了。我建议

validwords = set(validwords) # use a set for faster lookup times
words = sentence.split() # split by all whitespace
for word in words:
    # check whether word in validwords

如果您想用速记检查所有键入的单词是否有效，可以使用：

validwords = set(validwords) # use a set for faster lookup times
success = all(word in validwords for word in sentence.split())

当然，这不允许中间打印。你知道吗

Answer 3

the final five lines ... split up each letter in the sentence

这就是for循环。字符串是可由字符读取的。您循环了输入字符串，而不是拆分值。你知道吗

试试看

for word in sentence.split(" "):