My linux's gcc compiler not supporting boolean values

Question

I'm trying to make a function with return type as boolean...the syntax of the program seems to be correct but the compiler is giving errors....

The header files I've included are:

#include<stdio.h>
#include<stdlib.h>

the function I've created is:

34.bool checknull(struct node* node){
35.    if ( node != NULL )
36.        return TRUE;
37.       
38.    return false;
39.}

and what I'm getting at compile time is

bininsertion.c:34:1: error: unknown type name ‘bool’
bininsertion.c: In function ‘checknull’:
bininsertion.c:36:10: error: ‘TRUE’ undeclared (first use in this function)
bininsertion.c:36:10: note: each undeclared identifier is reported only once for each  function it appears in
bininsertion.c:38:9: error: ‘false’ undeclared (first use in this function)

I've tried "TRUE,false" both in small and capital letters but doesn't seem to work...

Solution

You should include <stdbool.h> if you want bool, true and false. Also it's true, not TRUE.

---

If you don't want to include stdbool.h you can just use the slightly ugly _Bool.

Comments

[Sabre.Tooth]

including stdbool.h solves my problem...thanx for that...and can you please explain the slightly ugly part i.e. how to use "_Bool" ( Syntax and an example )...

[cnicutar]

@Sabre.Tooth Use it like a normal type. So wherever you would write bool you could also write _Bool. The fact is _Bool is the "real" type, introduced in C99 and bool is just an alias. They couldn't introduce bool since it wasn't a reserved keyword in previous standards so it would have broken programs already using it.

[Sabre.Tooth]

using _Bool I still have to include stdbool.h because compiler treats "true" and "false" as undeclared variables...thnxxx for the help...

[cnicutar]

@Sabre.Tooth Yeah, or you can use 1 and 0. But by all means, I recommend stdbool.h.

[geekybedouin]

aha.. I just made some search.. bool is a datatype in C++.. :) the edit button isn't workin though..