I know that every compiler has different sizes for different data types. Does anybody know the sizes in bytes of: short int long int unsigned int signed int unsigned short int unsinged long int In Microsoft Visual C++ 6. I have checked the documentation in MSDN but canot find much info on this. Thanks for the help :-) ~Steve~

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Original post by steveharper101
I know that every compiler has different sizes for different data types.

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Incorrect. Data type sizes are defined by hardware platform. The only guarantee in C++ is that:
sizeof(char) < sizeof(short int) < sizeof(int) <= sizeof(long int) <= sizeof(float) < sizeof(double).

For Win32:

short int           16long  int           32unsigned int        32signed int          32unsigned short int  16unsinged long int   32 

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Thanks to Kylotan for the idea!

Just do this




sizeof() is handy to know about.

Regards.

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sizeof(long int) <= sizeof(float)

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Not sure about any guarantee of that.
But for all other comparisons I agree.

How come long integers and integers are the same!? Doesn''t that defeat the whole purpose of using "long?"

/me punches computer



--------------------
Matthew Calabrese
Realtime 3D Orchestra:
Programmer, Composer,
and 3D Artist/Animator
"I can see the music..."

I would add that although knowing the sizes of the various datatypes is very useful information, you should never explicitly put a concrete size in your program. Instead you should just use the sizeof() operator any time you''d need the size of a particular type.

The reason for this is that if you just use sizeof() in every case, it is much less likely that your program will crash and burn if you are trying to migrate to a system with different sizes for the various types.

-D

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Original post by Matt Calabrese
How come long integers and integers are the same!? Doesn''t that defeat the whole purpose of using "long?"

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They are currently the same because int defaults to long, it depends on you compiler. Don''t count on defaults though. As soon as we will start using 64 bit operating systems you''d probably have int default to int64 (in new compilers).

Output from the above program on Tru64:

The size of
short int is 2 bytes
long int is 8 bytes
unsigned int is 4 bytes
signed int is 4 bytes
unsigned short int is 2 bytes
unsigned long int is 8 bytes

See, long *is* useful

Matt Calabrese: on 16-bit systems such as MS-DOS an "int == 16-bits" and "long == 32-bits". it''s really, old school and probably a moot point now.

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