Dynamic array or not

[Era Scarecrow]

On Sunday, 16 January 2022 at 15:32:41 UTC, Salih Dincer wrote:
> If count is not equal to 8 I get weird results! The reason of 
> course, is the free():
> // [93947717336544, 1, 2, 3, 4, 5, 6]

I wonder if you're seeing something you're not suppose to as part 
of the internals; Typically malloc for 16bit allocation to my 
understanding worked a little different, where you had 2 bytes 
BEFORE the memory block which specified a size, and if it was 
negative then it was a size of free memory (*This allowed a 64k 
block to have multiple allocations and de-allocations*). So you 
might have: **64, [64 bytes of data], -1024, [1024 unallocated 
memory],32,[32 bytes of allocated data, etc]**. in the above if 
you deallocated the 64 byte block, it would just become -1090 
(*merging the next free block, 1024+64+2*). This would also 
explain why double freeing would break since it would be 
referring to free size and throw a fit, or it was no longer a 
length malloc/free could use.

Also malloc if it returns anything guarantees at least that size, 
you might ask for 7 bytes but get 16 and the others is just 
ignored.

Is this how the 32/64bit malloc/free work? Not sure, it wouldn't 
be unreal for Java and others to pre-allocate say a megabyte and 
then quickly give/manage a smaller block and extending or getting 
another block later.

Though I'm sure others here have given better/more exact on 
internals or how allocation works in D.