python - 删除子字符串时出现问题

Question

所以我试图从用户输入中删除子字符串(数字和特殊字符)，然后反转整个输入字符串。数字删除工作正常，但特殊字符没有。请看一下。

en_word = input()
x = 0
y = 0
f_character = ["1", "2", "3", "4", "5", "6", "7", "8", "9", "!", "@", "$", "%", "^", "&", "*", "(", 
")", "-"]
while f_character[x] in en_word:
    en_word = en_word.replace(f_character[x], "")
    x += 1
print(en_word[:: -1])

输入

123o%l$leh321

预期产出

hello

实际产量

hel$l%o 

Answer 1

只要字母不在单词中，您的 while 循环就会退出 - '4' 就是这种情况 - 所有其他的都不会被检查。
使固定:

en_word = "123o%l$leh321" 
y = 0
f_character = ["1", "2", "3", "4", "5", "6", "7", "8", "9", 
               "!", "@", "$", "%", "^", "&", "*", "(", ")", "-"]
for c in f_character:
    en_word = en_word.replace(c, "") 
print(en_word[:: -1])

有一个更好的方法来做到这一点，使用 str.translate 和 str.maketrans :

replacer = str.maketrans("", "", "123456789!@$%^&*()-")
en_word = "123o%l$leh321" 

print(en_word.translate(replacer)[::-1])  # hello

Doku str.maketrans :

This static method returns a translation table usable for str.translate.

If there is only one argument, it must be a dictionary mapping Unicode ordinals (integers) or characters (strings of length 1) to Unicode ordinals, strings (of arbitrary lengths) or None. Character keys will then be converted to ordinals.

If there are two arguments, they must be strings of equal length, and in the resulting dictionary, each character in x will be mapped to the character at the same position in y. If there is a third argument, it must be a string, whose characters will be mapped to None in the result.