什么会被这一行，为什么进行打印？ [英] What will be printed by this line and why?

问题描述

什么会被这一行打印？

 的printf（你好\\ N）| （输出（再见\\ n）||的printf（世界\\ n））;
 

测试后，印：

 你好
再见
 

但我仍然不知道为什么，仍然坚持它，任何暗示将非常AP preciated！顺便说一下我知道的printf（）返回输出的字符数，但仍然没有得到背后的逻辑。

解决方案

  | - 位OR运算符
|| - 逻辑或操作符的printf（你好\\ N）| （输出（再见\\ n）||的printf（世界\\ n））;
 

在这种情况下，无论是的printf（你好\\ n）和的printf（再见\\ n）它们之间|既然你已经使用>将被执行。因为它是按位操作，都将被执行。此外的printf 返回打印的字符数。因此，在你的情况，的printf（你好\\ N）|的printf（再见\\ n）将导致 6 | 8 = 0110 | 1000 = 1110 = 14（十进制）。

因此​​，前pression变得等同于 14 ||的printf（世界\\ n）。自14（即非零）本身符合逻辑或检查，就不会继续的printf（世界\\ n）这将是6。

What will be printed by this line?

printf("hello\n") | (printf("goodbye\n") || printf("world\n"));

After tested, it printed:

hello
goodbye

But I still don't know why and still stuck on it, any hints will be really appreciated! By the way I know that printf() returns the number of characters output but still do not get the logic behind that.

解决方案

|  - Bitwise OR operator
|| - Logical OR operator

printf("hello\n") | (printf("goodbye\n") || printf("world\n"));

In this case, both printf("hello\n") and printf("goodbye\n") will be executed since you have used | between them. Since it is bitwise operation, both will be executed. Also printf returns the number of characters printed. Hence in your case, printf("hello\n") | printf("goodbye\n") will result in 6 | 8 = 0110 | 1000 = 1110 = 14 (in decimal).

Hence the expression becomes equivalent to 14 || printf("world\n"). Since 14 (being non-zero) itself satisfies the Logical OR check, it will not proceed to printf("world\n") which would be 6.

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