Re: sprintf and 64-bit integers
Re: sprintf and 64-bit integers
- Subject: Re: sprintf and 64-bit integers
- From: Clark Cox <email@hidden>
- Date: Sun, 13 Sep 2009 20:20:20 +0200
On Sun, Sep 13, 2009 at 8:10 PM, email@hidden
<email@hidden> wrote:
> On Sun, Sep 13, 2009 at 8:01 PM, Bill Bumgarner <email@hidden> wrote:
>> On Sep 13, 2009, at 10:59 AM, email@hidden wrote:
>> I'm updating my code for Snow Leopard and ran into this problem. The
>>>
>>> app crashes at this line:
>>>
>>> sprintf(str, "%d", val);
>>>
>>> where val is a CFIndex. According to the string programming guide here...
>>>
>>>
>>> http://developer.apple.com/mac/library/documentation/Cocoa/Conceptual/Strings/Articles/formatSpecifiers.html
>>>
>>> ...I need to cast my CFIndex to long and replace the %d format
>>> specifier to %ld. I tried that but still got the crash. So I kept
>>> trying with all the format specifiers in the book, declaring my
>>> variable a NSInteger, unsigned int, etc, but no matter what the app
>>> kept crashing. The only that that actually worked was %lx, but then I
>>> get the numbers all wrong. It seems that sprintf only accepts 32-bit
>>> integers. Is this correct? If so, what's the workaround? I'm compiling
>>> for both 10.5 and 10.6. Advice appreciated, thanks.
>>
>> You are off in the weeds.
>>
>> There is nothing about a value conversion that could cause a crash. Wrong
>> value? Sure. But not a crash. Thus, the formatting string is *not* causing
>> a crash.
>>
>> The problem is almost assuredly that 'str' is pointing to garbage,
>> uninitialized or otherwise wrong.
>>
>> Post the code for how str is created.
>>
>> b.bum
>
> Sorry, str is simply created like this:
>
> char str[10];
> sprintf(str, "%d", val);
Are you positive that val is a nine digit number? If not, then you've
got a buffer overrun. This could have been failing in 32-bit as well,
but you were running off the end of the buffer by a smaller amount.
--
Clark S. Cox III
email@hidden
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