是否必须在C和C ++中转义制表符字符？ [英] Is it mandatory to escape tabulator characters in C and C++?

问题描述

在C和C ++（以及其他几种语言）中，字符和字符串常量中的水平制表符（ASCII代码9）以转义形式表示为'\t' \t。但是，我经常在字符串文字中键入未转义的制表符字符，例如在A&＃x0009; B（betreen中有一个TAB A 和 B ），至少clang ++似乎并不麻烦 - 字符串似乎等效于A \tB。我更喜欢非转义的版本，因为长缩进的多行字符串在源代码中更好的可读性。

In C and C++ (and several other languages) horizontal tabulators (ASCII code 9) in character and string constants are denoted in escaped form as '\t' and "\t". However, I am regularly typing the unescaped tabulator character in string literals as for example in "A B" (there is a TAB in betreen A and B), and at least clang++ does not seem to bother - the string seems to be equivalent to "A\tB". I like the unescaped version better since long indented multi-line strings are better readable in the source code.

现在我问自己这是否在C和C ++或者只是我的编译器支持。如何可移植是字符和字符串常量中的非转义制表符？

Now I am asking myself whether this is generally legal in C and C++ or just supported by my compiler. How portable are unescaped tabulators in character and string constants?

令人惊讶的是，我找不到这个看似简单的问题的答案，无论是谷歌还是stackoverflow（我只是发现< a href =http://stackoverflow.com/questions/14297477/how-do-you-insert-a-tab-in-a-string>这个模糊的相关问题）。

Surprisingly I could not find an answer to this seemingly simple question, neither with Google nor on stackoverflow (I just found this vaguely related question).

推荐答案

是的，您可以在字符串或字符文字中包含制表符字符，至少根据C ++ 11。允许的字符包括（我强调）

Yes, you can include a tab character in a string or character literal, at least according to C++11. The allowed characters include (with my emphasis):

源字符集的任何成员b双引号，反斜杠 \ 或换行字符

any member of the source character set except the double-quote ", backslash \, or new-line character

（从 C ++ 11 standard ，附件A.2）

，源字符集包括：

空格字符，表示水平标签，垂直标签，换页符和换行符的控制字符以及以下91个图形字符

the space character, the control characters representing horizontal tab, vertical tab, form feed, and new-line, plus the following 91 graphical characters

（来自 C ++ 11 standard ，paragraph 2.3.1）

(from C++11 standard, paragraph 2.3.1)

更新：对于C99，答案也是肯定的，措辞是不同的，但基本上说同样的事情：

UPDATE: I've just noticed that you're asking about two different languages. For C99, the answer is also yes. The wording is different, but basically says the same thing:

在字符常量或字符串字面量中，执行字符集的成员应由源字符集或[...]的对应成员表示

In a character constant or string literal, members of the execution character set shall be represented by corresponding members of the source character set or [...]

其中源字符集和执行字符集都包含

where both the source and execution character sets include

标签，垂直标签和
表单Feed。

control characters representing horizontal tab, vertical tab, and form feed.

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