Question

What is the C equivalent of this C# code?

[StructLayout(LayoutKind.Explicit)]
struct Test
{
    [FieldOffset(0)] int a;  // Integer at byte offset 0
    [FieldOffset(1)] int b;  // Integer at byte offset 1
    [FieldOffset(3)] int c;  // Integer at byte offset 3
};

_{(I don’t care if it’s non-portable, e.g. int is assumed to be 4 bytes, etc.)}

Answer 1

This seems to work fine under Visual Studio:

#pragma pack(push)

#pragma pack(1)
typedef union
{
    int a;
    struct
    {
        char unused0;
        int b;
    };
    struct
    {
        char unused1;
        char unused2;
        char unused3;
        int c;
    };
} Test;

#pragma pack(pop)