iOS正则表达式：未知的转义序列“\ |” [英] iOS Regex: Unknown escape sequence "\|"

问题描述

我收到一个奇怪的警告，因此我的正则表达式搜索无效。这是行：

I'm getting a weird warning, and as a result my regex search isn't working. Here's the line:

NSRange r = [HTML rangeOfString:@"\|(.*)\|" options:NSRegularExpressionSearch];

其中 HTML 是我的字符串确定包含上述正则表达式的单个匹配。

Where HTML is a string that I'm sure contains a single match for the above regex.

警告仅在第一次出现\ |时出现，而不是两者都出现。

The warning is only on the first occurrence of "\|", not on both.

非常感谢任何帮助！

推荐答案

您收到警告，因为 \ | 不是Objective-C（或C或C ++）中的有效转义序列。编译器忽略了这一点而只是使用原始的 | 字符，所以你实际传入的字符串是 @|（。*） |。

You're getting the warning because \| is not a valid escape sequence in Objective-C (or C or C++ for that matter). The compiler is ignoring that and just using a raw | character instead, so the string you're actually passing in is @"|(.*)|".

要获得所需的行为，您必须转义源代码中的反斜杠，以便正则表达式引擎看到文字反斜杠并将 | 字符解释为文字而不是替换，例如 @\\ |（。*）\\ |。

To get the behavior you want, you have to escape the backslash in your source code so that the regex engine sees the literal backslash and interprets the | character as a literal instead of as alternation, e.g. @"\\|(.*)\\|".

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