/Zp (Struct Member Alignment)
Controls how the members of a structure are packed into memory and specifies the same packing for all structures in a module.
When you specify this option, each structure member after the first is stored on either the size of the member type or n-byte boundaries (where n is 1, 2, 4, 8, or 16), whichever is smaller.
The available values are described in the following table.
Packs structures on 1-byte boundaries. Same as /Zp.
Packs structures on 2-byte boundaries.
Packs structures on 4-byte boundaries.
Packs structures on 8-byte boundaries (default).
Packs structures on 16-byte boundaries.
You should not use this option unless you have specific alignment requirements.
You can also use pack to control structure packing. For more information about alignment, see:
To set this compiler option in the Visual Studio development environment
Open the project's Property Pages dialog box. For details, see How to: Open Project Property Pages.
Click the C/C++ folder.
Click the Code Generation property page.
Modify the Struct Member Alignment property.