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malloc() troubles!!!!!!!!!

General and Gameplay Programming Programming

Started by Coleco July 26, 2001 11:07 PM

3 comments, last by Coleco 22 years, 9 months ago

Coleco

164

Author

July 26, 2001 11:07 PM

Ok, here''s the problem. I am trying to allocate some memory. Here is the code:



int *MAP;
unsigned int mapsize;

mapsize = (width * height * layers) * 4;  // this is ok, i checked...contains 960

MAP = (int *)malloc(mapsize * sizeof(int));

Now, when I display sizeof(MAP) it *always* returns 4 bytes! No matter what, MAP is always 4 bytes... Anoyone know what I am doing wrong? BTW, I am using Borland C++ Builder if that helps. Thanks! -Coleco

~ c o l ec o ~

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Martee

476

July 26, 2001 11:39 PM

MAP is a pointer to an int, which has the constant size of 4 bytes. You aren''t doing anything wrong

~~~~~~~~~~
Martee

ReactOS - an Open-source operating system compatible with Windows NT apps and drivers

Martee

476

July 26, 2001 11:40 PM

Side note: sizeof() is normally used only with the names of data types (e.g. sizeof(int)), not with variables themselves.

~~~~~~~~~~
Martee

ReactOS - an Open-source operating system compatible with Windows NT apps and drivers

Dactylos

122

July 27, 2001 12:13 AM

try using _msize() (or is it msize()) to get the size of the memory-chunk allocated. This size might be slightly larger than the number of bytes you asked for, depending on alignment issues and whether you''re using the debug heap-alloc functions etc...

Beer Hunter

712

July 27, 2001 02:57 AM

For malloc() in bcb, this works when I try it:

#define ALLOCATED_SIZE(x) (*(((unsigned int*)x)-1)-6)

The amount you initially specify in malloc seems to be rounded up to the nearest multiple of 4, and at least 8 bytes.

malloc() troubles!!!!!!!!!

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