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Strange C problem

Started by Kranman Dec 19, 2001 at 6:32 PM 4 replies 700+ views

Original Post

Dec 19, 2001 at 6:32 PM

When I execute this code, I get 4 byte numbers out! Console->Echo() outputs text to the console.

unsigned int *Data = new unsigned int[num];
fread(Data, 2, num, file)
Console->Echo("Data[0] = %x", Data[0]);

This doesnt seem possible - and the extra bytes are what should have been the next element''s data, so it''s reading 4 bytes into it... A memory problem?

Null and Void

163

Null and Void

Dec 19, 2001 at 6:42 PM

In a 32bit system with an average C compiler an "unsigned int" is 4 bytes, not 2. You should be using "sizeof(unsigned int)" where you use 2 or using "sizeof(unsigned short)" there and changing every "long" to "short" (a short is normally 2 bytes in a 32bit system with an average C compiler).

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jenova

Dec 19, 2001 at 6:46 PM

okay: i am assuming a lot here (which could make an ass out of you and me).

assuming: Windows, Intel x86, VisualStudio 4.0 to 6.0, etc.

unsigned int = 32 bits or 4 bytes.
unsigned long = 32 bits or 4 bytes.
unsigned short = 16 bits or 2 bytes.

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jenova

Dec 19, 2001 at 6:47 PM

Null and Void: 3 seconds. u bastard. j/k. nice answer.

To the vast majority of mankind, nothing is more agreeable than to escape the need for mental exertion... To most people, nothing is more troublesome than the effort of thinking.

Kranman

Author

Kranman

Dec 19, 2001 at 7:37 PM

Hm.. I remember reading in some (apparently old) docs that short was the same length as int. How mislead I was...

Thanks.

Null and Void

163

Null and Void

Dec 19, 2001 at 7:47 PM

quote:
Original post by Kranman
Hm.. I remember reading in some (apparently old) docs that short was the same length as int. How mislead I was...

They weren''t lying, they were simply refering to the common 16bit systems and compilers. The only rule for the sizes of integer data types in C is: short <= int <= long.

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