How to set variable padding bytes?

[xlbao123]

For example, I have such struct:

struct chunk_t {
    u32 size;
    .... //others
    u8 paddings[size - size of others];
};

how to make this work? Thanks.

[paxcut]

padding is a built in type measured in bytes so just

struct chunk_t {
    u32 size;
    .... //others
    padding[size - size of others];
};

[xlbao123]

Thanks for your reply. So how to calculate the total other's size? or is there some api to get the current file offset.

[paxcut]

Your welcome. The current file offset (aka as the cursor offset) is denoted by the symbol $ which is readable and write-able.
so

   padding[size - $];

[paxcut]

no sorry, i don't know what im thinking. ok. this seems to work

struct Test {
    s128 start = $;
    u8 size;
    u8 data;
    u32 t[3];
    s32 length = $ - start;
    if(size > length)
        padding[size-length];
};

[xlbao123]

struct chunk_t {
    char id[4];
    u32 size;
    u32 chunk_end = $ + size;

    if (id == "ACTN") {
    } else if (id == "ARGS") {
    } ...
    
    padding[chunk_end - $];
};

It seems to work. Thanks.