pack pragma | Microsoft Docs
https://docs.microsoft.com/en-us/cpp/preprocessor/pack
pack takes effect at the first struct, union, or class declaration after the pragma is seen. pack has no effect on definitions. Calling pack with no arguments sets n to the value set in the compiler option /Zp. If the compiler option isn't set, the default value is 8 for x86, ARM, and ARM64. The default is 16 for x64 native.
DA: 73 PA: 14 MOZ Rank: 77