python 验证用户输入的字符，并迭代字符在句子中出现的次数

gblwokeq 于 2022-11-21 发布在 Python

关注(0)|答案(3)|浏览(118)

while循环和for循环可以单独工作，但是将它们组合起来并不能产生所需的输出。我希望用户输入一个句子，然后输入一个字符。字符必须作为一个单一的1字符输入，如果不是，那么程序应该再次询问。

sentence = input("Type sentence: ")
sentence = sentence.lower()
singleCharacter = input("Type character: ")

char = 0

while len(singleCharacter) != 1:
    singleCharacter = input('Enter a single character: ')
    for i in sentence:
        if i == singleCharacter:
            char += 1

print(singleCharacter,"appears",char,"times in your sentence")

python

来源：https://stackoverflow.com/questions/74502810/validate-user-input-of-character-and-iterate-how-many-times-character-exists-in

3条答案

按热度按时间

sc4hvdpw1#

您在此代码块中遇到的问题：

while len(singleCharacter) != 1:
    singleCharacter = input('Enter a single character: ')
    for i in sentence:
        if i == singleCharacter:
            char += 1

只有当你第一次输入一个以上的字符时，它才会给予你想要的输出，否则它不会进入for循环来计算while循环条件len(singleCharacter) != 1内的字符数，然后返回初始字符数0。因此，要按预期工作，你应该把for循环用于计算while循环外的字符数：

while len(singleCharacter) != 1:
    singleCharacter = input('Enter a single character: ')
for i in sentence:
    if i == singleCharacter:
        char += 1

输出量：

Type sentence: Hello World!
Type character: l
l appears 3 times in your sentence

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ogsagwnx2#

类似于：

sentence = input("Type sentence: ")
sentence = sentence.lower()
singleCharacter = input("Type character: ")

char = 0

while len(singleCharacter) != 1:
    singleCharacter = input('Enter a single character: ')

print(sum([1 for c in sentence if c == singleCharacter]))

应该做你想做的事。

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ix0qys7i3#

只要将for循环从while循环中取出，它就会正常工作

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