Question

C++,

so I have this class

https://www.dropbox.com/s/s3ww1xopw5b42xa/Screenshot%202015-11-30%2000.17.34.png?dl=0

can someone please explain to me what is this '&'
right here:
https://www.dropbox.com/s/5g2tprliy9ji466/Screenshot%202015-11-30%2000.19.11.png?dl=0

thanks

Answer 1

& is a pointer just a refrence

Answer 2

are u familiar with the top command?

top() - return top item and its syntex is
top(StackEntry & item)

The item can be anything...or nothing. So in your case, there is nothing to return so it is blank. But the & separator must still be there.

Read more from here: ftp://cseftp.tc.uvu.edu/CNS/fairclde/Fall%202009/CS%202420/Slides/chapter%2002%20Object-Oriented%20Data%20Structures.pptx

Answer 3

yeah i agree but in general & means a pointer. sometimes it can refer to a location what ever its type integer.. string... or whatever. tight @superdavesuper ?

Answer 4

@ikram002p correct - it is just "something" there available for whatever purpose. in the above linked example:

ErrorCode Stack::top(StackEntry & item)const

{
// Pre: None
// Post: If not empty, top item returned
// If empty, underflow returned
ErrorCode outcome = success;
if(count == 0)
outcome = underflow;
else
item = entry[count - 1];
return outcome;
}//End top()

So item is used to store the previous entry.
if necessary...

Answer 5

so if I just leave it like this (&) (not &item) will it compile ?

also what's that pre and post ?????

Answer 6

thanks a lot for answering to me

Answer 7

@Christos it will compile just fine. sorry i didnt see any pre or post in ur codes.

Answer 8

I know there weren't , I am just asking cause I see that a lot

// Pre: None
// Post: .....

Answer 9

sorry i cant tell w/o seeing the codes...

Answer 10

here is the code

Answer 11

ErrorCode Stack::top(StackEntry & item)const

{
// Pre: None
// Post: If not empty, top item returned
// If empty, underflow returned
ErrorCode outcome = success;
if(count == 0)
outcome = underflow;
else
item = entry[count - 1];
return outcome;
}//End top()

So item is used to store the previous entry.
if necessary...

Answer 12

Oh @Christos
i just cut & paste from the example n didnt remember wats in there lol

Answer 13

That whole section:

// Pre: None
// Post: If not empty, top item returned
// If empty, underflow returned

contains just comments and explains how the stacks operate ;)

Answer 14

Nice slides!!!

Answer 15

pre means before and post means after

Answer 16

yup yup @Christos

Answer 17

thanks