如何检查字符串中的特殊字符? [英] How to check a string for a special character?

问题描述

我只能在我的程序中使用一个字符串，如果它不包含除下划线 _ 之外的特殊字符.我该如何检查?

I can only use a string in my program if it contains no special characters except underscore _. How can I check this?

我尝试使用 unicodedata 库.但是特殊字符只是被标准字符替换了.

I tried using unicodedata library. But the special characters just got replaced by standard characters.

推荐答案

你可以像这样使用 string.punctuation 和 any 函数

You can use string.punctuation and any function like this

import string
invalidChars = set(string.punctuation.replace("_", ""))
if any(char in invalidChars for char in word):
    print "Invalid"
else:
    print "Valid"

有了这条线

invalidChars = set(string.punctuation.replace("_", ""))

我们正在准备一个不允许使用的标点符号列表.由于您希望允许 _，我们正在从列表中删除 _ 并准备新的集合为 invalidChars.因为在集合中查找速度更快.

we are preparing a list of punctuation characters which are not allowed. As you want _ to be allowed, we are removing _ from the list and preparing new set as invalidChars. Because lookups are faster in sets.

any 函数将返回True.

正如评论中所问，这是正则表达式解决方案.取自 https://stackoverflow.com/a/336220/1903116

As asked in the comments, this is the regular expression solution. Regular expression taken from https://stackoverflow.com/a/336220/1903116

word = "Welcome"
import re
print "Valid" if re.match("^[a-zA-Z0-9_]*$", word) else "Invalid"

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