yesterday i had the follow code:
NSInteger test = arc4random_uniform(10)-5;
if i checked via debugger whats inside test, sometimes it was not a number between -5 and 5. Sometime it was a random big integer.
After i changed the code to this:
NSInteger test = arc4random_uniform(10);
test -= 5;
i was only get a number between -5 and 5. I'm pretty new to Objectiv C and normaly i only write C / C++. But this makes no sense for me.
Can someone explain what happend?
The arc4Random family of functions return u_int32_t. The "u_" means unsigned, and determines the type of the expression with the literal 5. So that first expression will (about half the time, for randoms < 5) produce an unsigned negative, which will be treated as nearly UINT_MAX.
The second expression casts the random as a signed int first, so the subsequent subtraction works as expected.