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Accessing structures in functions in C++

I have some functions that take in structures, amongst other things.
eg.
int winapi rectangle(SIZES *pInfo);

...where SIZES is a structure. How can I assign values to the variables of the Structure SIZES? I'v tried creating an object of type SIZES and assigning values using the (.)
SIZES MySizes; //create a Sizes object
*mySizesPtr=&mySizes, //pointer &mySizesRef=mySizes; //reference

mySizes.version = 0x03000000;

But I'm not sure that this is assigning the values to the right place.
Pls can i have a simple example of how to do this correctly. Pls help!

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xLs

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RONSLOW

Two ways...

int winapi rectangle(SIZES *pInfo) {
pInfo->xxxx = yyy;
}

or

int winapi rectangle(SIZES *pInfo) {
SIZES& sizes = *pInfo;
sizes.xxxx = yyyy;
}

The first accesses directly from the pointer with ->

The second uses a reference, and you can then use '.'

Both of the above will change the thing pointed to by pInfo.

If you take a COPY of the thing pointed to by pInfo and change that, then the original is unchanged.

kaushikg

Both person has replied correctly but RONSLOW's explanation is easy to understand.

Kelvin_King

what does the -> mean ?

RONSLOW

p->x is just shorthand for

(*p).x

ie. it dereferences the pointer to a struct and then gets the member of the struct.

or simpler...

ie. it does a '.' on the object pointed to by p

pointers are a tricky C concept for many to grasp.

even trickier for some is C++ references, which is what I used in the other example.

nicolac

ASKER

Thanks, I understand now :)