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Re: -[NSString stringWithCString:encoding:] memory management question
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Re: -[NSString stringWithCString:encoding:] memory management question


  • Subject: Re: -[NSString stringWithCString:encoding:] memory management question
  • From: Greg Parker <email@hidden>
  • Date: Wed, 11 Nov 2009 12:52:17 -0800

On Nov 11, 2009, at 11:58 AM, Hank Heijink (Mailinglists) wrote:
> So, I'm curious about how -[NSString initWithCString:encoding:] works. According to the documentation, it returns "An NSString object initialized using the characters from nullTerminatedCString." Does that mean it doesn't copy the bytes? Then what does it do? -[NSString initWithUTF8String] explicitly states that it returns "An NSString object initialized by copying the bytes from bytes."

-initWithCString:encoding: should copy the bytes. You can verify that yourself with a small test:

    char buf[10+1] = "0123456789";
    NSString *s = [[NSString alloc] initWithCString:buf encoding:NSASCIIStringEncoding];
    NSLog(@"before %@", s);
    memset(buf, 'x', 10);
    NSLog(@"after  %@", s);

If the bytes were not copied then `before` and `after` would differ.

I don't see any memory errors in your code. My next suspect would be memory errors in getMetadata() or getLengthOfMetadata(). Try replacing getLengthOfMetadata(...) with pcLength=10, and/or getMetadata(...) with memset(pBuffer, 'x', pcLength). If one of those changes makes the crash go away then those two functions look much more suspicious.


--
Greg Parker     email@hidden     Runtime Wrangler


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References: 
 >-[NSString stringWithCString:encoding:] memory management question (From: "Hank Heijink (Mailinglists)" <email@hidden>)

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