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#### 5.49.7 Structure-Packing Pragmas

For compatibility with Win32, GCC supports a set of `#pragma` directives which change the maximum alignment of members of structures (other than zero-width bitfields), unions, and classes subsequently defined. The n value below always is required to be a small power of two and specifies the new alignment in bytes.

1. `#pragma pack(`n`)` simply sets the new alignment.
2. `#pragma pack()` sets the alignment to the one that was in effect when compilation started (see also command line option `-fpack-struct[=<n>]` see Code Gen Options).
3. `#pragma pack(push[,`n`])` pushes the current alignment setting on an internal stack and then optionally sets the new alignment.
4. `#pragma pack(pop)` restores the alignment setting to the one saved at the top of the internal stack (and removes that stack entry). Note that `#pragma pack([`n`])` does not influence this internal stack; thus it is possible to have `#pragma pack(push)` followed by multiple `#pragma pack(`n`)` instances and finalized by a single `#pragma pack(pop)`.