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digitalmars.D.learn - need help to redefine packed c struct in d

reply Dakota <dakota gmail.com> writes:
```c
struct __attribute__((packed)) type1 {
     uint32_t        u32;
     uint8_t         u8;
     uint16_t        u16a;
     uint16_t        u16b;
     uint8_t         u8a;
     uint8_t         arr[14];
};

```

the struct size in C is 24:

I try `pragma(packed)` and `align(1):`, the d size always is 25.

how to fix this?
Sep 28
parent reply Johan <j j.nl> writes:
On Saturday, 28 September 2024 at 07:54:40 UTC, Dakota wrote:

 ```c
 struct __attribute__((packed)) type1 {
     uint32_t        u32;
     uint8_t         u8;
     uint16_t        u16a;
     uint16_t        u16b;
     uint8_t         u8a;
     uint8_t         arr[14];
 };

 ```

 the struct size in C is 24:

 I try `pragma(packed)` and `align(1):`, the d size always is 25.

 how to fix this?


Put the `align(1):` inside the struct definition.
https://d.godbolt.org/z/qqsK1ro9v

-Johan
Sep 28
parent Dakota <dakota gmail.com> writes:
On Saturday, 28 September 2024 at 08:35:39 UTC, Johan wrote:

 On Saturday, 28 September 2024 at 07:54:40 UTC, Dakota wrote:

 ```c
 struct __attribute__((packed)) type1 {
     uint32_t        u32;
     uint8_t         u8;
     uint16_t        u16a;
     uint16_t        u16b;
     uint8_t         u8a;
     uint8_t         arr[14];
 };

 ```

 the struct size in C is 24:

 I try `pragma(packed)` and `align(1):`, the d size always is 
 25.

 how to fix this?


 Put the `align(1):` inside the struct definition.
 https://d.godbolt.org/z/qqsK1ro9v

 -Johan


thanks, it work.
Sep 28