Is primitive data variable length limited by computer hardware ?

[lonelyplanet999]

Hi,

I'm studying 310-035 exam. The textbook available said that long data
type variable is of 64 bits (so are double type variable). However,
when I tested program in my Pentium 166 notebook w/ windows 98 OS, I
found that long data variable is only of 32 bits wide.

I found operation 1<<32 output 1 instead of 2 to the power of 32.

I would like to ask will java support 64 bits variables only if the
computer hardware (e.g. processor, data bus) supports 64 bits data
transfer ?

Tks

 

[Thomas Schodt]

Numeric literals are 32 bit integers.

Try this:

class longTest {
public static void main(String[] argv) {
System.out.println(1<<32);
System.out.println(1L<<32);
}
}

 

[Sudsy]

Hi,

I'm studying 310-035 exam. The textbook available said that long data
type variable is of 64 bits (so are double type variable). However,
when I tested program in my Pentium 166 notebook w/ windows 98 OS, I
found that long data variable is only of 32 bits wide.

I found operation 1<<32 output 1 instead of 2 to the power of 32.

Try 1L << 32 (the trailing L indicates that the number is long).

 

[Dale King]

Hi,

I'm studying 310-035 exam. The textbook available said that long data
type variable is of 64 bits (so are double type variable). However,
when I tested program in my Pentium 166 notebook w/ windows 98 OS, I
found that long data variable is only of 32 bits wide.

How did you find that out since it is not true.

I found operation 1<<32 output 1 instead of 2 to the power of 32.

Because the << operator takes the right hand operand and does a modulus with
the size of the left hand type. Since 1 is an int constant it has a width of
32 so a modulus of 32 is done with the right hand operand. That means 1 <<
32 is exactly the same as 1 << 0.

And note that this has no bearing on the question of longs being 64 bits
because your expression contained no long data types. If you try with a long
constant as in 1L you will find that 1L << 32 will give you the answer you
expect.

I would like to ask will java support 64 bits variables only if the
computer hardware (e.g. processor, data bus) supports 64 bits data
transfer ?

Perhpas for J2ME, but for J2SE long must be supported.

 

[Roedy Green]

I found operation 1<<32 output 1 instead of 2 to the power of 32.

see shiftless shift in http://mindprod.com/jgloss/gotchas.html#SHIFT

 

[Roedy Green]

I would like to ask will java support 64 bits variables only if the
computer hardware (e.g. processor, data bus) supports 64 bits data
transfer ?

No. long is always 64 bits. There is something wrong with your test,
Possibly failure to apply trailing Ls to your literals.

See http://mindprod.com/jgloss/literals.html

 

[=?ISO-8859-1?Q?Thomas_Gagn=E9?=]

What will jave do when the first 128-bit chips become available? Will
that be a long long?

No. long is always 64 bits.

<snip

 

[Roedy Green]

What will jave do when the first 128-bit chips become available? Will
that be a long long?

For addressing, 64 bits aught to hold us quite a while. The size of an
address is invisible in Java.

They could do that, mainly to avoid creating a new keyword. I would
prefer a new keyword, e.g. wide.

 

[Moonshadao]

The size of an
address is invisible in Java.

The size of your dick is invisible as well.

I would
prefer a new keyword, e.g. wide.

You would probably prefer a new dick too.

 

[nos]

intel has 128 floating point today
even 64 bit processors don't use all 64 bits for addressing