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Question about Pointers

Started by FrancoisSoft Sep 3, 2003 at 5:02 PM 6 replies 300+ views

Original Post

Sep 3, 2003 at 5:02 PM

Ok, when I allocate a buffer from the heap I usually try to use the sizeof operator to take the size of the buffer but I only get 4 when the buffer may be 1000 bytes in size. Why can''t I use sizeof on buffers allocated from the heap but I can use them on buffer allocated from the stack? Hey, don''t forget to visit my page... by clicking here!

drekkar

Sep 3, 2003 at 5:03 PM

4 is the size of the pointer, not the memory it is pointing to

antareus

Sep 3, 2003 at 5:48 PM

sizeof is evaluated at compile time, not runtime.

If you want someone to keep track of how big your buffers are then you should be using a std::vector.

JonStelly

Sep 3, 2003 at 6:19 PM

Or you could override the new operator and implement some sort of allocation tracking, but chances are that if you need something like that, you''re doing something else wrong.

FrancoisSoft

Author

FrancoisSoft

Sep 3, 2003 at 6:31 PM

quote:
Original post by JonStelly
Or you could override the new operator and implement some sort of allocation tracking, but chances are that if you need something like that, you''re doing something else wrong.

I don''t think I want to do this.

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Ready4Dis

Sep 3, 2003 at 6:41 PM

Well, just store the size that you''re allocating in a variable.. obviuosly you know the size that you are allocating, and the size of the data type that you''re allocating, so you know how much memory it''s using.

antareus

Sep 3, 2003 at 7:06 PM

Problem is the token type should be outside the allowable range of values. This leads to silliness like a member function called getchar returning an int because it has to express failure somehow.

*cough* exceptions people, exceptions*cough*

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