[SOLVED] About the 'unsigned long long' type

lesca · 10-23-2010, 07:41 PM

Hello

I am reading stdio.h to learn more functions and stardard declarations.

When I see atoll function, I find its return type is odd: long long int

And there are more functions return odd types, such as unsigned long int, unsigned long long int

What do they mean? Take 'long long' type for example, if long is 32 bits, does long long has 64-bit precision?

And I try to find some type like 'double double' but find nothing. Will it work if I use double double?

Thanks!

Sergei Steshenko · 10-23-2010, 08:08 PM

Quote:

Originally Posted by lesca

Hello

I am reading stdio.h to learn more functions and stardard declarations.

When I see atoll function, I find its return type is odd: long long int

And there are more functions return odd types, such as unsigned long int, unsigned long long int

What do they mean? Take 'long long' type for example, if long is 32 bits, does long long has 64-bit precision?

And I try to find some type like 'double double' but find nothing. Will it work if I use double double?

Thanks!

How about reading C99 standard ( http://www.open-std.org/JTC1/SC22/wg...docs/n1124.pdf ) first ?

johnsfine · 10-23-2010, 08:11 PM

In both x86 and x86_64 int is 32 bit and long long is 64 bit. I don't know what you can assume in other architectures.

I don't think there is a type double double. There is a type long double that might be a higher precision double, but it also might have the same precision as an ordinary double.

lesca · 10-24-2010, 06:49 AM

I think I understand your meanning.

And I will read the pdf!

Thank you very much!

lesca · 10-24-2010, 06:49 AM

I think I understand your meanning.

And I will read the pdf!

Thank you very much!