how to work with long int expressions in shell scripts

[madhavabk]

Hi All,

I am adding two large integer numbers and i am getting -ve output as expr will use 32 bit representation.

but do we have any command or tool that will evaluate expressions that contain larget ints.

Thanks,
Madhava

[A. Clay Stephenson · Accepted solution]

You can use bc to do calculations both integet and floating-point of unlimited precision.

VAL=$(echo "(300 * 8) + 5" | bc)
echo "Result = ${VAL}"

Man bc for details.

[Rodney Hills]

Within ksh or posix-sh you can use the typeset command to specify a integer type (long) and then use the "let" command to do arithmetic.

HTH

-- Rod Hills

[Peter Nikitka]

Hi,

if mean, how to enable 64bit integer arithmetic in the shell: you can't (as far as I know).

You'll have to use bc, dc or perl to do your computation.
If you set a shell variable to such a value, the result would be a string - so you can compare for equalness.

mfG Peter

[A. Clay Stephenson]

It would be better to do all the comparisons in bc as well since actual numeric comparisons can be done (integer or floating-point) without having to pad values as one would have to do in the shell.

[madhavabk]

Hi All,
Thanks for participation in my problem.
The problem is getting solved with bc command.

Thanks,
Madhava