Welcome to OGeek Q&A Community for programmer and developer-Open, Learning and Share
Welcome To Ask or Share your Answers For Others

Categories

0 votes
1.9k views
in Technique[技术] by (71.8m points)

what is the purpose of "(void) ( { CODE } )" in c?

In a generated piece of c code I found something like this (edited):

#include <stdio.h>

int main() {

  (void) (
    {
      int i = 1;
      int y = 2;

      printf("%d %d
", i,y);
    }
  );

  return 0;
}

I believe I have never seen the construct (void) ( { CODE } ) before, nor am I able to figure out what the purpose might be.

So, what does this construct do?

See Question&Answers more detail:os

与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…
Welcome To Ask or Share your Answers For Others

1 Reply

0 votes
by (71.8m points)

({ }) is a gcc extension called a statement expression.

http://gcc.gnu.org/onlinedocs/gcc/Statement-Exprs.html

A statement expression yields a value and the (void) cast is probably here to remove the compiler warning or to make explicit that the value of the statement expression is not used.

Now (void) ({ }) is the same as a simple compound statement {} and there is no point of using it.


与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…
OGeek|极客中国-欢迎来到极客的世界,一个免费开放的程序员编程交流平台!开放,进步,分享!让技术改变生活,让极客改变未来! Welcome to OGeek Q&A Community for programmer and developer-Open, Learning and Share
Click Here to Ask a Question

1.4m articles

1.4m replys

5 comments

57.0k users

...