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Re: Can an NSArray ever have a count of -1?
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Re: Can an NSArray ever have a count of -1?


  • Subject: Re: Can an NSArray ever have a count of -1?
  • From: Jean-Daniel Dupas <email@hidden>
  • Date: Fri, 19 Feb 2016 22:44:16 +0100

> Le 19 févr. 2016 à 22:29, Jens Alfke <email@hidden> a écrit :
>
>
>> On Feb 19, 2016, at 1:17 PM, Jim Adams <email@hidden> wrote:
>>
>>           SLogInfo(@"Starting csi %ld count %d", csi, sortedEvents.count);
>>
>> In the console I see:
>> INFO: Starting csi -1 count -1
>> The very next line crashes when the sortedEvents are accessed. What could cause the array to have a -1 count?
>
> You’re using the wrong format strings for both of those parameters.
>
> csi is 64-bit so you need %lld. The formatter sees %ld and thinks it’s 32-bit not 64-bit, so it skips the wrong amount of space on the stack when going to the next parameter, which is why you then get a bogus value for the count.
>
> Also, NSArray.count is of type NSUInteger, which is unsigned, and has different sizes on different platforms. The right format specifier is either %lu (in a 32-bit app) or %llu (in 64-bit).

Not exactly. %d is for 32 bit signed integer, but %ld is for signed long, and so is the right formatter for NSInteger value (which is a typedef alias of long) and 64 bit integer on 64 bit platform.

%lld is for signed long long and is the same as long for most platform.




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  • Follow-Ups:
    • Re: Can an NSArray ever have a count of -1?
      • From: Charles Srstka <email@hidden>
    • Re: Can an NSArray ever have a count of -1?
      • From: Jens Alfke <email@hidden>
    • Re: Can an NSArray ever have a count of -1?
      • From: Jim Adams <email@hidden>
References: 
 >Can an NSArray ever have a count of -1? (From: Jim Adams <email@hidden>)
 >Re: Can an NSArray ever have a count of -1? (From: Jens Alfke <email@hidden>)

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