Ruby 正则表达式中 A z 和 ^ $ 的区别 [英] Difference between A z and ^ $ in Ruby regular expressions
问题描述
在我阅读的文档中:
使用A和z匹配字符串的开头和结尾，^和$匹配一行的开头/结尾.
Use A and z to match the start and end of the string, ^ and $ match the start/end of a line.
我将应用正则表达式来检查用户提交的用户名(或电子邮件地址是否相同).我应该将哪个表达式与模型中的 validates_format_of 一起使用?我无法理解其中的区别:我一直使用 ^ 和 $ ...
I am going to apply a regular expression to check username (or e-mail is the same) submitted by user. Which expression should I use with validates_format_of in model? I can't understand the difference: I've always used ^ and $ ...
推荐答案
如果你依赖正则表达式进行验证，你总是想使用 A 和 z.^ 和 $ 只会匹配到一个换行符，这意味着他们可以使用像 me@example.com
<script>dangerous_stuff() 这样的电子邮件;</script> 并且仍然对其进行验证，因为正则表达式只能看到
之前的所有内容.
If you're depending on the regular expression for validation, you always want to use A and z. ^ and $ will only match up until a newline character, which means they could use an email like me@example.com
<script>dangerous_stuff();</script> and still have it validate, since the regex only sees everything before the
.
我的建议是事先从用户名或电子邮件中完全删除新行，因为几乎没有正当理由.然后你可以安全地使用 A z 或 ^ $.
My recommendation would just be completely stripping new lines from a username or email beforehand, since there's pretty much no legitimate reason for one. Then you can safely use EITHER A z or ^ $.
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