Linked Questions

457 votes

5 answers

218k views

I've been seeing that expression for over 10 years now. I've been trying to think what it's good for. Since I see it mostly in #defines, I assume it's good for inner scope variable declaration and for ...

242 votes

1 answer

155k views

Possible Duplicates: What’s the use of do while(0) when we define a macro? Why are there sometimes meaningless do/while and if/else statements in C/C++ macros? do { … } while (0) ...

151 votes

2 answers

66k views

Possible Duplicates: Do-While and if-else statements in C/C++ macros do { ... } while (0) — what is it good for? I'm reading the linux kernel and I found many macros like this: #define ...

45 votes

7 answers

25k views

Possible Duplicate: Why use apparently meaningless do-while and if-else statements in macros? Why is the do while(false) necessary in the macros below? #define LOG(message, ...) \ do { \ Lock<...

26 votes

6 answers

9k views

Possible Duplicates: What’s the use of do while(0) when we define a macro? Why are there sometimes meaningless do/while and if/else statements in C/C++ macros? C multi-line macro: do/...

29 votes

3 answers

26k views

Possible Duplicate: Why are there sometimes meaningless do/while and if/else statements in C/C++ macros? I met code like below: #define ev_io_init(ev,cb,fd,events) \ do { \ ev_init ((ev), (cb));...

13 votes

4 answers

11k views

Possible Duplicates: Why are there sometimes meaningless do/while and if/else statements in C/C++ macros? do { … } while (0) what is it good for? I'm working on some C code filled with ...

5 votes

5 answers

3k views

Possible Duplicate: Why are there sometimes meaningless do/while and if/else statements in C/C++ macros? When one needs to execute multiple statements within preprocessor macro, it's usually ...

7 votes

3 answers

5k views

Possible Duplicate: Do-While and if-else statements in C/C++ macros gcc (GCC) 4.7.2 c89 Hello, I have the following function-like macro and just wondering what is the preferred usage when using ...

6 votes

3 answers

1k views

As a C newbie I'm having trouble understanding the following code: #define errExit(msg) do { perror(msg); exit(EXIT_FAILURE); \ } while (0) I gathered that the reason ...

1 vote

3 answers

2k views

Lately, I see more and more code pieces that use the template of: do { ... some code ... } while (false); Why to do this? If I'm not mistaken, the code will run only one time so the loop is seem ...

1 vote

2 answers

1k views

I have noticed a programming style in Embedded C, used for firmware programming: #define WRITE_REGISTER(reg, value) \ do { \ write_to_register(reg, value); \ } while (0) ...

2 votes

2 answers

473 views

I recently saw a piece of C code including a macro of the following style: #define TOTO() \ do { \ do_something(); \ do_another_something(); \ } ...

3 votes

3 answers

987 views

What is the significance of do while loop when the condition inside the while loop is 0 i.e. always false. do { //some code implementation. }while(0); I have seen at many places this is being used. ...

1 vote

2 answers

2k views

Is it correct way to write a multiple statements in one Macro? #define AB() do { printf("hi"); } while(0)