sizeof with structures

lets say i have this structure

Code:

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struct example{int x, float y[2]}z[12],j[5];

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if i say

Code:

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sizeof(example) ;

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which size from all the above will return

i have one last query if i send to one function this:

Code:

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function_example( (void*)z);

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what actually i send here?
thanks

sizeof(example), funnily enough, will give you the size of (one) example (object).

In the second case, you are sending z (the array of examples, as a pointer to its first element) to your function.

thanks dude
have a nice day

Is there any way to know the real size of a struct?

sizeof (structname);

Really... you can easily look these things up in your C library documentation...

Quote:

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Originally Posted by CommonTater

sizeof (structname);

Really... you can easily look these things up in your C library documentation...

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There you go again telling people to look stuff up. Honestly, I don't know how you live with yourself. :rolleyes::tongue:

Quote:

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Originally Posted by CommonTater

sizeof (structname);

Really... you can easily look these things up in your C library documentation...

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From what i understood from the above post, this will return the size of one of the element in the struct, which is not the whole struct.

How about you read like Tater suggested, and try fiddling around with a sample program. Given the code from your first post, some interesting things to print out might be:

• sizeof(struct example)
• sizeof(z)
• sizeof(z[0])
• sizeof(z[0].x)
• sizeof(z[0].y)
• sizeof(z[0].y[0])
• sizeof(j)

EDIT:
> From what i understood from the above post, this will return the size of one of the element in the struct, which is not the whole struct.
And how did you come to this conclusion? You asked a question and Tater gave you an answer, and a correct one at that. How did you infer you're only getting one element of the struct?

Quote:

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Originally Posted by tabstop

sizeof(example), funnily enough, will give you the size of (one) example (object).

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Quote:

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Originally Posted by valthyx

From what i understood from the above post, this will return the size of one of the element in the struct, which is not the whole struct.

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Oh, my bad, I didn't even see tabstop's post. tabstop mispoke, the sizeof operator will always return the number of bytes for any operand. This is true for structures, arrays, native types ect.

So for sizeof(example) and sizeof(structname) will both return the same number; the size of the type in bytes.

sizeof(struct example) will give you the size of one struct example object, since that's what you asked for, the size of an example.

If you want (say) the size of the array z (in bytes, not in objects), then you can do sizeof(z).

Quote:

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Originally Posted by tabstop

sizeof(struct example) will give you the size of one struct example object, since that's what you asked for, the size of an example.

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...in bytes.

EDIT: Oops...I guess I was the one confused about what the OP was asking. :tongue:

Quote:

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Originally Posted by valthyx

From what i understood from the above post, this will return the size of one of the element in the struct, which is not the whole struct.

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It returns the entire size of one struct or union ...

If you have an array of structs... just multiply by the number of elements in the array.

Quote:

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Originally Posted by AndrewHunter

...in bytes.

EDIT: Oops...I guess I was the one confused about what the OP was asking. :tongue:

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I don't think so... I'm thinking our OP friend has confused "struct" with "array"... in particular by calling an array of structs a struct.