Primitive data type - long and integer

[henry leu]

Hi,

The error message that the Java compiler gives me is confusing.

I purposely have a numeric (integer) literal that is outside the integer range. I know it will give me an error message as follows:

long number = 666666666666; // error

Hello.java: error: integer number too large
                long l = 666666666666;
                         ^
1 error

------------------------------------------------------
But if I purposely give a numeric (long) literal that is also outside of the long range, the message I get is also the integer too large.
Why doesn't Java say long too large?

long number = 666666666666L; // error


Hello.java: error: integer number too large
                long l = 666666666666L;
                         ^
1 error

[Campbell Ritchie]

How did you get an error for your second line of code? It is correct.

[henry leu]

Campbell Ritchie wrote:How did you get an error for your second line of code? It is correct.

Yes, 2nd line is correct. I put the wrong code.

The error code should be this one.

long number = 666666666666666666666666L; // error

Just wondering why the error message says integer number too large.

Why not long number too large?

[Stephan van Hulst]

The word "integer" refers to the mathematical concept of a number that is "whole".

Java uses the keyword int to declare a variable that can hold integers up to 2^16-1, and it uses long to hold "long integers" up to 2^32-1, but they are both "integers".

[henry leu]

Stephan van Hulst wrote:The word "integer" refers to the mathematical concept of a number that is "whole".

Java uses the keyword int to declare a variable that can hold integers up to 2^16-1, and it uses long to hold "long integers" up to 2^32-1, but they are both "integers".

Thank you Stephan!

[Matthew Bendford]

Stephan van Hulst wrote:The word "integer" refers to the mathematical concept of a number that is "whole".

Java uses the keyword int to declare a variable that can hold integers up to 2^16-1, and it uses long to hold "long integers" up to 2^32-1, but they are both "integers".

This doesn't sound right to me. As far as I'm aware, ints are 32 bits and longs are 64 bits. This results in the ranges of:
int: -2^31 - 2^31-1
long: -2^63 - 2^63-1
The missing 32nd/64th bit is used to designate if a number is either positive or negative.

[Campbell Ritchie]

You're right; the 16 must be a misprint. The 31st bit doesn't only determine the sign; it represents a value of −(2³¹). That is different from an S&M representation where the leftmost bit inverts the sign of the rest of the number.

[Tim Holloway]

Stephan van Hulst wrote:The word "integer" refers to the mathematical concept of a number that is "whole".

Java uses the keyword int to declare a variable that can hold integers up to 2^16-1, and it uses long to hold "long integers" up to 2^32-1, but they are both "integers".

No, Java does NOT base itself on 16-bit integers. A Java int is 32 bits worth of data (31 + sign). A Java long is 64 bits worth of data. The days of 16-bit integers are long gone outside of specialty processors.

[Stephan van Hulst]

I wrote that in a less than rested state of mind. The corrections of course are correct.

[Tim Holloway]

Stephan van Hulst wrote:I wrote that in a less than rested state of mind. The corrections of course are correct.

Thank you. Too many times, I give incorrect corrections, alas.

Still, I departed the 16-bit world after only a brief sojourn there. IBM mainframes were 32-bits back then. The Motorola MC68000 CPU could be used in either 16 or 32-bit mode (Apple used 16 bits, Commodore used 32 and I was an Amiga geek), so it was only around 1990 that I regularly worked with 16-bit processors and my thought patterns developed accordingly.