Python-如何使用re匹配整个字符串 [英] Python- how do I use re to match a whole string

问题描述

我正在验证用户输入的文本，以使其仅接受字母，而不接受数字.到目前为止，当我输入数字时(例如56)，我的代码可以正常工作，它警告我只能输入字母，而当我输入字母时，它不返回任何内容(就像它应该那样).我的问题是，当我开始输入字母后跟数字时，它会接受它. (s45).它的作用是接受第一个字母，但不接受整个字符串.我需要它来接受整个字符串.

I am validating the text input by a user so that it will only accept letters but not numbers. so far my code works fine when I type in a number (e.g. 56), it warns me that I should only type letters and when I type in letters it doesn't return anything (like it should do). My problem is that it accepts it when I start by typing letters followed by numbers e.g. (s45). what it does is accept the first letter but not the whole string. I need it to accept the whole string.

def letterCheck(aString):
    if len(aString) > 0:
        if re.match("[a-zA-Z]", aString) != None:
            return ""
    return "Enter letters only"

推荐答案

将其固定到开头和结尾，并匹配一个或多个字符:

Anchor it to the start and end, and match one or more characters:

if re.match("^[a-zA-Z]+$", aString):

在这里^锚定到字符串的开头，$锚定到字符串的末尾，并且+确保您匹配1个或多个字符.

Here ^ anchors to the start of the string, $ to the end, and + makes sure you match 1 or more characters.

最好使用 str.isalpha() 更好.无需在这里拿起沉重的正则表达式锤子:

You'd be better off just using str.isalpha() instead though. No need to reach for the hefty regular expression hammer here:

>>> 'foobar'.isalpha()
True
>>> 'foobar42'.isalpha()
False
>>> ''.isalpha()
False

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