Hi,
Somebody recently asked me to implement the sizeof operator, i.e. to
write a function that accepts a parameter of any type, and without
using the sizeof operator, should be able to return the size occupied
by that datatype in memory in bytes. Thanks :)
Abhishek Srivastava
32  2564 
* Abhishek Srivastava:
>
Somebody recently asked me to implement the sizeof operator, i.e. to
write a function that accepts a parameter of any type, and without
using the sizeof operator, should be able to return the size occupied
by that datatype in memory in bytes. Thanks :)
This sounds like HOMEWORK.
One must hope that nobody provides source code for you (although they
invariably do, to show off their ability to code trivial things).
Hint: array.
--
A: Because it messes up the order in which people normally read text.
Q: Why is it such a bad thing?
A: Top-posting.
Q: What is the most annoying thing on usenet and in e-mail?
Abhishek Srivastava wrote:
Hi,
Somebody recently asked me to implement the sizeof operator, i.e. to
write a function that accepts a parameter of any type, and without
using the sizeof operator, should be able to return the size occupied
by that datatype in memory in bytes. Thanks :)
Note that the difference in address between two adjacent elements of an
array is equal to the size of an element.
Tom
Hi Alf P. Steinbach :)
This is not homework. Just wanted to know because I couldn't think of
the solution. Hmmmm.... your hint is to use an array, still pondering
over that. Thanks anyway.
Alf P. Steinbach wrote:
* Abhishek Srivastava:
Somebody recently asked me to implement the sizeof operator, i.e. to
write a function that accepts a parameter of any type, and without
using the sizeof operator, should be able to return the size occupied
by that datatype in memory in bytes. Thanks :)
This sounds like HOMEWORK.
One must hope that nobody provides source code for you (although they
invariably do, to show off their ability to code trivial things).
Hint: array.
--
A: Because it messes up the order in which people normally read text.
Q: Why is it such a bad thing?
A: Top-posting.
Q: What is the most annoying thing on usenet and in e-mail?
Abhishek Srivastava posted:
Hi,
Somebody recently asked me to implement the sizeof operator, i.e. to
write a function that accepts a parameter of any type, and without
using the sizeof operator, should be able to return the size occupied
by that datatype in memory in bytes. Thanks :)
Abhishek Srivastava
#include <cstddef>
template<class T>
struct SizeOfHelper {
T array[2];
};
#define SizeOf(T) offsetof(SizeOf Helper<T>, array[1])
I don't mind doing this homework question for people, because it's
utterly pointless.
--
Frederick Gotham
Frederick Gotham wrote:
Abhishek Srivastava posted:
>>Hi,
Somebody recently asked me to implement the sizeof operator, i.e. to
write a function that accepts a parameter of any type, and without
using the sizeof operator, should be able to return the size occupied
by that datatype in memory in bytes. Thanks :)
Abhishek Srivastava
#include <cstddef>
template<class T>
struct SizeOfHelper {
T array[2];
};
#define SizeOf(T) offsetof(SizeOf Helper<T>, array[1])
I don't mind doing this homework question for people, because it's
utterly pointless.
Your implementation is incorrect in any case. offsetof is only defined
for POD types.
Tom
Abhishek Srivastava wrote:
Hi,
Somebody recently asked me to implement the sizeof operator, i.e. to
write a function that accepts a parameter of any type, and without
using the sizeof operator, should be able to return the size occupied
by that datatype in memory in bytes.
Interesting story.
Thanks :)
What for?
Tom Widmer posted:
Your implementation is incorrect in any case. offsetof is only defined
for POD types.
Yes, and thankfully, my type is a POD.
--
Frederick Gotham
Frederick Gotham wrote:
Tom Widmer posted:
>Your implementation is incorrect in any case. offsetof is only defined
for POD types.
Yes, and thankfully, my type is a POD.
There's a second problem too; offsetof is defined for
member-designators, and "array[1]" isn't a member-designator.
Tom
Frederick Gotham wrote:
Tom Widmer posted:
>Your implementation is incorrect in any case. offsetof is only defined
for POD types.
Yes, and thankfully, my type is a POD.
Do you mean SizeOfHelper<Ti s a POD type? It is a POD type if and
only if T is a POD type.
Tom This thread has been closed and replies have been disabled. Please start a new discussion. Similar topics | |
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