val = &(a->b.c) not same as x=a->b; val = &(x.c) in C?

user_9407535 0
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I have the following code in C:

char *val = &((file->chunk).a);

but when I do

struct Chunk data = file->chunk;
char *val = &(data.a);

it doesn't yield the same result in val. Why aren't these two the same?

pointers struct c
2 Answers

These two pieces of code have val pointing to two different places.

In the first example, you have an instance of struct Chunk at file->chuck and take the address of one of its members. In the second example, you copy the contents of file->chunk to a separate instance of struct Chunk which resides in a different memory location.

While the contents of these two structs may be the same, they are separate objects each with their own address. So file->chunk.a and data.a will have different addresses.

user_16871190

In the second case, you are creating a distinct struct Chunk instead of referring to the one inside file. Substitute:

struct Chunk *data = &(file->chunk);
char *val = &(data->a);

to get the same address.

user_39215130
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