如何输入“：” regexp中的（“冒号”）？ [英] How to type ":" ("colon") in regexp?

问题描述

：（冒号）在regexp中有特殊含义，但我需要按原样使用它，如 [A-Za Z0-9， - ：] * 。
我试图逃避它，但这不起作用 [A-Za-z0-9。， - \：] *

: ("colon") has a special meaning in regexp, but I need to use it as is, like [A-Za-z0-9.,-:]*. I have tried to escape it, but this does not work [A-Za-z0-9.,-\:]*

推荐答案

在大多数正则表达式实现（包括Java）中，：没有特殊含义，也没有内部也不在字符类之外。

In most regex implementations (including Java's), : has no special meaning, neither inside nor outside a character class.

您的问题很可能是因为 - 充当范围运算符在你班上：

Your problem is most likely due to the fact the - acts as a range operator in your class:

[A-Za-z0-9.,-:]*

其中， - ：匹配之间的所有ascii字符，'和'：'。请注意，它仍然与文字'：'相匹配！

where ,-: matches all ascii characters between ',' and ':'. Note that it still matches the literal ':' however!

请改为尝试：

[A-Za-z0-9.,:-]*

通过在课程的开头或结尾放置 - ，它与文字 - 匹配。正如Keoki Zee的评论中提到的，你也可以逃避课程中的 - ，但大多数人只是在最后添加它。

By placing - at the start or the end of the class, it matches the literal "-". As mentioned in the comments by Keoki Zee, you can also escape the - inside the class, but most people simply add it at the end.

演示：

public class Test {
    public static void main(String[] args) {
        System.out.println("8:".matches("[,-:]+"));      // true: '8' is in the range ','..':'
        System.out.println("8:".matches("[,:-]+"));      // false: '8' does not match ',' or ':' or '-'
        System.out.println(",,-,:,:".matches("[,:-]+")); // true: all chars match ',' or ':' or '-'
    }
}

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