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cpreprocessorpragma

Meaning of #pragma pack(2)

What does

#pragma pack(2)

do? What does it mean?

Solution

  • It means that structs, unions or classes are aligned by 2 bytes. That means, the following struct will use 3 bytes in memory instead of 2:

    struct MyStruct
{
    char Field1;
    char Field2;
};

    The following will use 4 bytes:

    struct MyStruct
{
    WORD Field1;
    WORD Field2;
};

    More here: http://msdn.microsoft.com/en-us/library/2e70t5y1%28v=vs.80%29.aspx. Important: Read about the problems and use it only if you know what you are doing and you need it ;-)