When should I use _aligned_malloc()?

Question

I've been reading the legacy code,which invloves in the customized memory pooling system, then I found that the code uses _aligned_malloc. I wonder what is this function and when do I have to use it.

Answer 1

Have you checked the MSDN documentation? You can find the respective entry here.

Answer 2

This function is useful when the alignment of your memory allocation is important to you. Alignment means that the numerical value of the pointer returned must be evenly divisible by a certain number, ie. ((unsigned int)ptr) % alignment should evaluate to 0.

An example of a reason for wanting a certain alignment is to use the data with the SSE instruction set on x86 where the data must be aligned to a multiple 16.

Answer 3

Thanks all of you.

I did read MSDN but what I wanted was the answer like "An example of a reason for wanting a certain alignment is to use the data with the SSE instruction set on x86 where the data must be aligned to a multiple 16".

I finally understood what those code means. thanks again.

Answer 4

Another example - ARM processor. It requires to align all data to 4 bytes.