Question

有了以下法典,这部法典的产出是什么?

#include <stdio.h>

int main() {
        printf("Hello world
"); // \
        printf("What s the meaning of this?");
        return 0;
}

Answer 1

The backslash at the end of the 4th line is escaping the following new line so that they become one continuous line. And because we can see the // beginning a comment, the 5th line is commented out.

也就是说,你的法典相当于:

#include <stdio.h>

int main() {
        printf("Hello world
"); // printf("What s the meaning of this?");
        return 0;
}

产出只是一个新行的“Hello世界”。

<><>Edit>: 正如Erik和Pmg两人都说过的那样,在C99而不是C89就是如此。信贷到期的信贷。

在翻译的第二阶段(ISO/IEC 9899:1999 §5.1.1.2):

Each instance of a backslash character () immediately followed by a new-line character is deleted, splicing physical source lines to form logical source lines.

Answer 2

It s "Hello world ". Didn t you try? Line continuation (and e.g trigraphs) are well documented, look it up. A syntax highlighting editor (e.g. Visual Studio with VA X) will make this obvious.

注:这一工程在C99和C++-not进行。 C89

Answer 3

拖拉的后.导致下线延伸到下线,以压倒下,即使它含有一部分评论。这几乎永远是无意的(除非它带有蓄意的混淆,否则就会造成ug,除非下行完全是白人空间或评论本身。

This happens because line-splicing occurs in translation phase 2, while removing comments happens in phase 3.

新的汇编者将警告单线评论将持续到下行(我并不确切地说,可能需要多少警告):

GCC 4.5.1 (MinGW)

C:	emp	est.c:4:34: warning: multi-line comment

MSVC 9 (VS 2008) or 10 (VS 2010):

C:	emp	est.c(5) : warning C4010: single-line comment contains line-continuation character

Answer 4

C: emp est.c:4:34: 警告:多线评论

C: emp est.c(5) : warning C4010: single-line comment contains line-continuation character

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