下面的正方形是做什么的?
[w+-.]+
以上正则、 w+- + 和 w+- + 和 w+- + 的输出相同,但我不明白为什么?
测试字符串
sadkfj-dslk.sdjklf!sdljf
你能解释给我听吗?
同样,因为反斜线是多余的;当 给定的regex 查找这些字符中的一个或多个字符 : - 不表示有效的字符范围( 即 w (一个字字符)、 - (dash) 或 . (周期)。 由于在 - 之前的反斜是不必要的,无论是否包含在内。
在方括号内,连字符有特殊含义(“范围”),因此,字面连字符应作为 - 逃避。然而,视你特定的regex 引擎而定,你可能会与未逃脱的语法脱节,因为在此特定情况下没有模糊之处。
(例如, Perl 将接受两个版本并产生预期结果, 但使用 < code> 使用警告; 它将抱怨缺失的反斜线 。 )
这符合单词字符 [0- 9a- z- A- ] (w 匹配单词字符), 或 + 字符, 或连字符( 跳出 - ), 或 完全停止, 所有这一切都重复不止一次 。
这意味着它会匹配含有普通字母、下划线、加号、加号、连字符或完整停止的字符串, 只要没有空格。 简言之, 对我来说, 这似乎是从 URL 识别字符串以查找数据库条目的函数 。
没有区别, 因为逃离- 没有必要, 因为没有字符匹配“ + to ”, 所以逃逸或逃逸, 没有什么区别 。
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