Objective-C : BOOL vs bool

c objective-c types boolean
Francescu picture Francescu · Feb 12, 2009 · Viewed 184.5k times · Source

I saw the "new type" BOOL (YES, NO).

I read that this type is almost like a char.

For testing I did :

NSLog(@"Size of BOOL %d", sizeof(BOOL));
NSLog(@"Size of bool %d", sizeof(bool));

Good to see that both logs display "1" (sometimes in C++ bool is an int and its sizeof is 4)

So I was just wondering if there were some issues with the bool type or something ?

Can I just use bool (that seems to work) without losing speed?

Answer

Barry Wark picture Barry Wark · Feb 13, 2009

From the definition in objc.h:

#if (TARGET_OS_IPHONE && __LP64__)  ||  TARGET_OS_WATCH
typedef bool BOOL;
#else
typedef signed char BOOL; 
// BOOL is explicitly signed so @encode(BOOL) == "c" rather than "C" 
// even if -funsigned-char is used.
#endif

#define YES ((BOOL)1)
#define NO  ((BOOL)0)

So, yes, you can assume that BOOL is a char. You can use the (C99) bool type, but all of Apple's Objective-C frameworks and most Objective-C/Cocoa code uses BOOL, so you'll save yourself headache if the typedef ever changes by just using BOOL.

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