在 while 循环中将字母附加到列表中

Question

我正在尝试将句子的第一个单词附加到一个空列表中。 当前代码如下：

sentence = input("Enter sentence: ")

subject = []
print (subject)

x = 0
while True:
    letter = sentence[x]
    if letter != " ":
        print (letter)
        subject.append(letter)
        x = x + 1

print (subject)

它目前打印：

Enter sentence: Cherries are red fruit

[]
C
h
e
r
r
i
e
s

它似乎忽略了我将结果附加到空列表的尝试...请帮助！

Answer 1

你最好使用for循环，它不容易出错：

sentence = input('Enter sentence: ')

subject = []
print(subject)

for letter in sentence:
    if letter == ' ':
        break
    else:
        print(letter)
        subject.append(letter)

print(subject)

如果你想把一个句子分成单词，有一个str.split方法，它可以在简单的情况下帮助你：

words = sentence.split()
first_word = words[0] if words else None
print(first_word)

Answer 2

为什么不使用split()函数而不是一次附加一个字母：

sentence = input("Enter sentence: ")
split_sentence = sentence.split(" ")
subject = []
subject.append(split_sentence[0])
print (subject)

或者更简单：

sentence = input("Enter sentence: ").split(" ")
subject = []
subject.append(sentence[0])
print (subject)

或者即使您只想要一个输入，您也不必附加

sentence = input("Enter sentence: ").split(" ")
subject = sentence[0]
print (subject)

split() ，拆分由参数定义的字符串并返回一个列表。

Answer 3

使用 while 循环：

sentence='Nice weather outside'
subject = []
x = 0
while x < len(sentence):
    letter = sentence[x]
    subject.append(letter)
    x = x + 1
print(subject)