Advise how and where to find information about #pragma pack(pop)

[Pje]

Hello All,

Can you guys please help me where I can find the info on what the pragma pack means how and when to use it I am new to c and ingeneral to arm controllers ,any help hints are appreciated, I googled but a lot of confusing results for a person with no knowledge about this topic 

Thanks again

[Andrew Neil · Accepted solution]

You need the compiler documentation.

As you've posted in STM32CubeIDE, the compiler it uses is GCC - so you need the GCC documentation:

https://gcc.gnu.org/onlinedocs/gcc/Diagnostic-Pragmas.html

https://gcc.gnu.org/onlinedocs/gcc/extensions-to-the-c-language-family/pragmas-accepted-by-gcc.html

Specifically:

https://gcc.gnu.org/onlinedocs/gcc/extensions-to-the-c-language-family/pragmas-accepted-by-gcc.html#structure-layout-pragmas

Structure packing can also be achieved using __attribute__:

https://www.gnu.org/software/c-intro-and-ref/manual/html_node/Packed-Structures.html

https://gcc.gnu.org/onlinedocs/gcc-3.3/gcc/Type-Attributes.html

On structure packing/padding in general:

https://en.wikipedia.org/wiki/Data_structure_alignment

http://www.catb.org/esr/structure-packing/

[Pje]

Dear Andrew,

Thank you so much for your help it is much appreciated ,

Sorry for my late reply I was out of the country on work only goy back 2 days ago 

Thank you so much once again

Regards PJe

[Andrew Neil]

You're welcome.

Please mark the solution:

https://community.st.com/t5/community-guidelines/help-others-to-solve-their-issues/ta-p/575256