c++ - C 和 C++ 中反斜杠后的空白字符

Question

C 和 C++ 标准对反斜杠后的空白字符(或几个字符)有何规定？它是否保证无论如何都会加入行？

int main()
{
    // Comment \ 
    int foo;
}

在这种情况下，MSVC 和 gcc 的工作方式不同。

Answer 1

作为引用，标准引述是(§2.2/1，删节，强调我的):

Phases of Translation

[...]
2. Each instance of a backslash character (\) immediately followed by a new-line character is deleted, splicing physical source lines to form logical source lines. Only the last backslash on any physical source line shall be eligible for being part of such a splice. If, as a result, a character sequence that matches the syntax of a universal-character-name is produced, the behavior is undefined. A source file that is not empty and that does not end in a new-line character, or that ends in a new-line character immediately preceded by a backslash character before any such splicing takes place, shall be processed as if an additional new-line character were appended to the file.
[...]

其他答案提到的实现定义部分在“换行”的定义中。

(请注意，直到第 3 阶段才替换注释，因此在此代码中:

int main()
{
    int x = 0;

    // assuming the definition of new-line is as expected, this function
    // will return 0, not 5 (no whitespace after this backslash: ) \
    x = 5;

    return x;
}

x = 5; 将附加到评论的末尾，然后最终删除。)