Cocoa: I need help with some code?

Question

Hello,

I was going through some code that I downloaded off the internet (Got it here)

I am confused with this line of code... What exactly is it doing?

#define N_RANDOM_WORDS (sizeof(randomWords)/sizeof(NSString *))

Here is the array of "randomWords":

static NSString *randomWords[] = {
@"Hello",
@"World",
@"Some",
@"Random",
@"Words",
@"Blarg",
@"Poop",
@"Something",
@"Zoom zoom",
@"Beeeep",
};

Thanks

Answer 1

sizeof(randomWords) gives the number of bytes taken up by the array. Each element of the array is an NSString pointer. sizeof(NSString*) gives the size of each pointer. So dividing the total size by the size of each element gives the number of elements.

N_RANDOM_WORDS is a macro being defined. Wherever it is used, the expression sizeof(randomWords)/sizeof(NSString*) will be inserted in its place by the preprocessor. This is usually how constants are defined in C or Objective C.

For more information on macros in C (and Objective C), here's a nice tutorial.

Answer 2

One NSString* takes sizeof(NSString*) bytes. The size of randomWords is N * sizeof(NSString). So solving for N, you get N = sizeof(randomWords)/sizeof(NSString *).