How to use marshal.structuretoptr to append records using structured types.

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I am new to Visual Basic and exploring using Marshal.StructureToPtr to store structures into allocated memory before writing to file.

My question is that if I write more than one record (using structure type) using this function, would the second record replace the first in the memory allocated? In other words, does data append or replace everytime I use the function?

What I have tried:

Have not tried as the function doesn't provide any indication that this is possible.

Posted 25-Feb-17 13:48pm

Member 13006206

Updated 25-Feb-17 14:40pm

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Dave Kreskowiak · Answer 1 · 2017-02-25T14:40:00

So long as you keep providing a correct pointer to where you want the structure copied to and you unmanaged code supports you appending this data to any existing data, sure, you can use it to "append" data in your block of memory. It's not going to do it for you. YOU must perform the pointer math to move the pointer appropriately top where the next structure is going to be copied to.

If you don't move the pointer then you're going to overwrite what was there before. If you're not careful you're going to have a leak as references to the old object are not going to be decremented properly.