Cocoa:NSUInteger vs unsigned int When the Range is Very Small?

Question

I have an unsigned int variable and it can only have the values of 0 -> 30. What should I use: unsigned int or NSUInteger? (for both 32 and 64 bit)

Answer 1

It makes very little difference in your case, there is no right or wrong. I might use an NSUInteger, just to match with Cocoa API stuff.

NSUInteger is defined like this:

#if __LP64__ || TARGET_OS_EMBEDDED || TARGET_OS_IPHONE || TARGET_OS_WIN32 || NS_BUILD_32_LIKE_64
typedef long NSInteger;
typedef unsigned long NSUInteger;
#else
typedef int NSInteger;
typedef unsigned int NSUInteger;
#endif

Answer 2

Running this:

    int sizeLong = sizeof(unsigned long);
    int sizeInt = sizeof(unsigned int);
    NSLog(@"%d, %d", sizeLong, sizeInt);

on 64bits gives: 8, 4 on 32 bits gives: 4, 4 So that yes, on 64 bits unsigned long (NSUInteger) takes twice as much memory as NSUInteger on 32 bits.

Answer 3

I’d go with either NSUInteger (as the idiomatic general unsigned integer type in Cocoa) or uint8_t (if size matters). If I expected to be using 0–30 values in several places for the same type of data, I’d typedef it to describe what it represents.