Using true and false in C

c coding-style
Tom picture Tom · Feb 12, 2010 · Viewed 175.6k times · Source

As far as I can see there are 3 ways to use booleans in c

  1. with the bool type, from then using true and false
  2. defining using preprocessor #define FALSE 0 ... #define TRUE !(FALSE)
  3. Just to use constants directly, i.e. 1 and 0

are there other methods I missed? What are the pros and cons of the different methods?

I suppose the fastest would be number 3, 2 is more easily readable still (although bitwise negation will slightly add to overhead), 1 is most readable not compatible with all compilers.

Answer

Chris Jester-Young picture Chris Jester-Young · Feb 12, 2010

Just include <stdbool.h> if your system provides it. That defines a number of macros, including bool, false, and true (defined to _Bool, 0, and 1 respectively). See section 7.16 of C99 for more details.

Related questions

Checking for NULL pointer in C/C++

In a recent code review, a contributor is trying to enforce that all NULL checks on pointers be performed in the following manner: int * some_ptr; // ... if (some_ptr == NULL) { // Handle null-pointer error } else { // Proceed } instead of int * some_ptr; // ... …

Read More
Auto-indent spaces with C in vim?

I've been somewhat spoiled using Eclipse and java. I started using vim to do C coding in a linux environment, is there a way to have vim automatically do the proper spacing for blocks? So after typing a { the next …

Read More
A free tool to check C/C++ source code against a set of coding standards?

It looks quite easy to find such a tool for Java (Checkstyle, JCSC), but I can't seem to find one for C/C++. I am not looking for a lint-like static code analyzer, I only would like to check against …

Read More