Re: Can an NSArray ever have a count of -1?
Re: Can an NSArray ever have a count of -1?
- Subject: Re: Can an NSArray ever have a count of -1?
- From: Jim Adams <email@hidden>
- Date: Fri, 19 Feb 2016 22:12:16 +0000
- Thread-topic: Can an NSArray ever have a count of -1?
It really was the wrong format specifier. Turns out the crash was on the next line where I used %d and %@ together. The -1 was an indicator of the issue but not the cause of my crash.
Thanks for the quick look. I will try that warning flag. I haven’t changed any of those flags so it may very well be warning me.
On Feb 19, 2016, at 4:44 PM, Jean-Daniel Dupas <email@hidden<mailto:email@hidden>> wrote:
Le 19 févr. 2016 à 22:29, Jens Alfke <email@hidden<mailto:email@hidden>> a écrit :
On Feb 19, 2016, at 1:17 PM, Jim Adams <email@hidden<mailto: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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