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Asked: 2026-05-27T13:29:04+00:00

I need to set the struct alignment in XCode to 1-byte packing, and adding

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I need to set the struct alignment in XCode to 1-byte packing, and adding the pragma “#pragma pack(1)” doesn’t seem to have any effect.
Is there another way to do this?
I have to read legacy data, so hand-packing is not an option.
Thanks,

Bill

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1 Answer

  1. Editorial Team

    XCode is using GCC, so you must use GCC specific instructions : http://gcc.gnu.org/onlinedocs/gcc-3.2/gcc/Type-Attributes.html

    For example :

      struct S { char f[3]; } __attribute__ ((aligned (1)));

    This struct will thus be aligned with a minimum of 1 byte.

    You also have the packed attribute, which specify that no padding should be added.

    EDIT

    I forget to mention but as @Stephen Chu mentionned it, MSVC style pragma are also supported by GCC : http://gcc.gnu.org/onlinedocs/gcc/Structure_002dPacking-Pragmas.html

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