Whilst true, it pales compared to the inefficiency of executing external
commands. I've always preferred the (( a = a + 1 )) construct because it
is slightly more readable. Nice to know that there's a performance
reason for doing it too. Thanks for sharing.
Phil
Roland Mainz wrote:
Peter Tribble wrote:
On Thu, Sep 10, 2009 at 8:38 AM, Raymond Wong<raym...@gmail.com> wrote:
[snip]
while read a
do
line=$(($line+1))
done
This will run even faster if you remove the '$', put the assignment
inside the arithmetric expression and declare "line" as integer
variable, e.g. ...
-- snip --
integer line=0
while read a ; do
(( line=line+1 ))
done
-- snip --
These optimisations make sure that the shell won't do any unneccesary
string-to-integer and integer-to-string conversions which consume lots
of time. For floating-point values they are even a huge problem since
strings used base10 and the internal IEEE754 floats use base2 and the
string-to-float and float-to-string conversions trigger rounding
problems...
----
Bye,
Roland
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