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Re: malloc during selectAll -> crash
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Re: malloc during selectAll -> crash


  • Subject: Re: malloc during selectAll -> crash
  • From: John Stiles <email@hidden>
  • Date: Fri, 12 May 2006 07:05:28 -0700



Jim Correia wrote:
On May 11, 2006, at 10:31 AM, Ryan Britton wrote:

On May 11, 2006, at 7:16 AM, Lorenzo wrote:

////////////////////// NSMutableArray *items = [NSMutableArray array]; NSIndexSet *selectedRows = [self selectedRowIndexes]; unsigned int i, totItems = [selectedRows count]; if(totItems == 0) return items ;

unsigned int *buf = malloc(totItems);

You're allocating a buffer here of totItems bytes. An int is not a single byte so you're bound to get a memory access error when you attempt to access something outside your malloc'd memory. Try replacing this with something like unsigned int *buf = (unsigned int *) malloc(totlItems * sizeof(unsigned int));

And in fact, when allocating space for an array, calloc may be a natural choice.


     #include <stdlib.h>

     void *
     malloc(size_t size);

     void *
     calloc(size_t count, size_t size);
If you don't mind a smattering of ObjC++ then this is easily the cleanest approach--no casts or sizeof needed:
unsigned int * buf = new unsigned int[totItems];
/// ... use it ...
delete [] buf; // don't forget the [] here!


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References: 
 >malloc during selectAll -> crash (From: Lorenzo <email@hidden>)
 >Re: malloc during selectAll -> crash (From: Ryan Britton <email@hidden>)
 >Re: malloc during selectAll -> crash (From: Jim Correia <email@hidden>)

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