hi guys,

Is there anyway to use sizeof within a local function when
I've passed an array to this function.

When I use a function call and function heading like so....

someFunct(int* const array)
{
cout << sizeof array/ size(int);
}

in the effort to determine the number of
elements in the array, I get 4, which is
the size of memory in bytes of an int data type

I think I can only use the
cout << sizeof array / sizeof(int)

in main, is this so?

Thanks much!

OK,

So maybe if I clear things up I wont confuse everyone.

I'm trying to pass two arrays to a function. Among other things
I want to compare the size of the array(# of elements)
which can be accomplished by
sizeof array / sizeof(int)

This works fine in main(), but once I reference the arrays
to a local function and I run the same code,
I get a value of 1.

Breaking it down,

sizeof array results in 4
sizeof(int) results in 4
4/4 results in 1

So, I guess in the local function, the first sizeof call
is working on the first element of the array and
not the whole array as in main( )

Does anyone know a trick for this, I am sure there must be.

Thanks

When you pass the array to the reference variable, it becomes a pointer(sort of). So, when you say 'size of', you get the size of the reference variable(an int here) and not the size of the array.

As a generall guide, sizeof will only tell you the size of things whose size is known at compile time. As soon as you pass an array as an argument, as UltimaGuy said, it basically becomes a pointer, and (without complicated analysis of the code) the C compiler has no way of knowing the size of the block of memory a pointer is pointing to.

Alex

smart pointers are a class available from www.boost.org

There are other implementations of smart pointers as well. The idea is that these pointers know about things like array bounds and can return the length of arrays of objects.

Thanks jim mcnamara, I've joined in the boost's mailing list. I am going to play with it as this smart pointer concept is quite new to me.

thanks everyone,!
I just guess I will not be running
sizeof() on referenced arrays anytime soon....