@（AT）的文件路径标志/串 [英] @(at) sign in file path/string

问题描述

可能重复：结果
  什么是在.NET中字符串前面的@？

我有以下的code：

new Attachment(Request.PhysicalApplicationPath + @"pdf\" + pdfItem.Value)

什么是 @ 标志呢？

推荐答案

它无关的文件路径。它改变琴弦的逃逸行为。

It has nothing to do with filepath. It changes the escaping behavior of strings.

在与一个字符串$ P $ @ pfixed 的转义序列开始 \\ 被禁用。这是方便，因为文件路径 \\ 是路径分隔符，你不希望它启动一个转义序列。

In a string literal prefixed with @ the escape sequences starting with \ are disabled. This is convenient for filepaths since \ is the path separator and you don't want it to start an escape sequence.

在一个正常的字符串，你将不得不逃离 \\ 到 \\\\ 让你的例子看起来像这样 PDF \\\\。但是，由于它与 pfixed @ $ P $需要逃逸的唯一字符是（被转义为，）和 \\ 可以简单地出现。

In a normal string you would have to escape \ into \\ so your example would look like this "pdf\\". But since it's prefixed with @ the only character that needs escaping is " (which is escaped as "") and the \ can simply appear.

此功能方便了含有字符串的文字 \\ 如文件路径或正则表达式。

This feature is convenient for strings literals containing \ such as filepaths or regexes.

有关您简单的例子增益不那么大，但是像你有一个完整的路径C：\\\\ ABC \\\\ \\\\ CDE DEF然后 @C：\\ ABC \\ CDE \\ DEF。看起来要好很多。

For your simple example the gain isn't that big, but image you have a full path "C:\\ABC\\CDE\\DEF" then @"C:\ABC\CDE\DEF" looks a lot nicer.

有关定期EX pressions这几乎是必须的。一个正则表达式通常包含几个，如果你需要逃避它们 \\ 转义其他字符已经和经常变得几乎无法读取。

For regular expressions it's almost a must. A regex typically contains several \ escaping other characters already and often becomes almost unreadable if you need to escape them.

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