Absolute value of NSInteger

问题:

Referring to Convert to absolute value in Objective-C I'm wondering if there are functions for NS typedefed types. Or is abs(NSInteger) okay? Is it architecture-safe?

回答1:

Use ABS() macro, which is defined in NSObjCRuntime.h, it is architecture-safe.

回答2:

You can use Foundation’s ABS() macro:

NSInteger a = 5;
NSInteger b = -5;
NSLog(@"%ld %ld", ABS(a), ABS(b));

回答3:

While the two posted answers are absolutely correct about using the ABS() macro, it should certainly be noted that NSIntegerMin, whose true absolute value can not be represented as an NSInteger returns itself when the ABS() function is called.

Presuming a 64-bit system:

NSLog(@"ld", ABS(NSIntegerMin)); 
// prints: -9223372036854775808

NSLog(@"%ld", ABS(NSIntegerMin + 1)); 
// prints: 9223372036854775807, which == NSIntegerMax

The same results will happen on a 32-bit system, but the numbers will be [phone] and -2147483648