adding 2 large integer numbers on ia64 gives negative results

[moonchild]

Hi All,

While adding two large integer numbers using expr command we discovered that the outcome becomes negative. (Small numbers are fine).

This happened on ALL our HP-UX ia64 servers.

Any idea?

Thank you in advance

[James R. Ferguson · Accepted solution]

HI:

This is due to 32-bit arithmetic. Use 'bc' or 'adb' or 'awk' or 'perl' to perform your arithmetic. The 'ksh' shell at 11.23 will do 64-bit arithmetic too.

Y=2147483647
# X=$(expr $Y + 1);echo $Xecho
-2147483648

# echo $Y|awk '{printf "%10.0f\n",$0+1}'
2147483648

Regards!

...JRF...

[Steven Schweda]

> This is due to 32-bit arithmetic. [...]

No, this is due to _signed_ arithmetic. The
number of bits merely determines what "large"
is.

When I was young, learning about computers
involved learning how computers count. (That
was back when computers were used mostly for
computation. It's been a while.) I gather
that this is less common now.

[Armin Kunaschik]

For big numbers use external commands like bc:

$ echo $((17179869184+17179869184))
0
$ echo "17179869184+17179869184"|bc
34359738368

My 2 cents,
Armin

PS: Please assign points if you find answers useful!

[moonchild]

see above