Xcode: Different behavior between swift Int and Objective-C int

Question

I'm trying to convert Swift function to Objective-C. This is the signature of the functions

Swift:

func hammingWeight(_ n: Int) -> Int

Objective-C

-(int) hammingWeight:(int) number

I'm passing this value to function/method:

00000000000000000000000000001011

In the case of Swift if I print the value of n it prints this:

p n
(Int) $R2 = 1011

In the case of Objective-C prints this:

p number
(int) $0 = 521

My question to you guys is why Objective-C is changing the value of I'm passing. It makes no sense to me. Any of you knows why this is happening or if there is a way around this?

I'll really appreciate your help with this.

This is the complete Objective-C implementation:

@interface DoSomething : NSObject
@end

@implementation DoSomething

-(int) hammingWeight:(int) number {
    NSLog(@"number %d", number);
}

@end

int main(int argc, char *argv[]) {
    @autoreleasepool {
        DoSomething *doIt = [DoSomething new];
        [doIt hammingWeight:00000000000000000000000000001011];
    }
}

Answer 1

The difference is that in (Objective-)c your given number is interpreted as octal due to the prefixed 0, while in Swift, it is interpreted as decimal.

For octal Int literals in Swift prefix 0o.

Information on octal Int literals in the Swift documentation
Information on octal int numbers in c documentation

// Swift:
(lldb) po 0o0000000000000000000000000001011;
521

(lldb) po 00000000000000000000000000001011;
1011

// Objective-C
(lldb) po 1011
1011

(lldb) po 01011
521