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The Struct Member Alignment (/Zpn) option 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.
You should not use this option unless you have specific alignment requirements.
| Command Line | Project Settings | Result |
| /Zp1 | 1 Byte | Packs structures on 1-byte boundaries |
| /Zp2 | 2 Bytes | Packs structures on 2-byte boundaries |
| /Zp4 | 4 Bytes | Packs structures on 4-byte boundaries |
| /Zp8 | 8 Bytes | Packs structures on 8-byte boundaries (default) |
| /Zp16 | 16 Bytes | Packs structures on 16-byte boundaries |
| /Zp | Not applicable | Specifies the same packing for all structures in a module. |
To find this option in the development environment, click Settings on the Project menu. Then click the C/C++ tab, and click Code Generation in the Category box.
You can also use #pragma pack to control structure packing.