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Re: [bug-gawk] Does gawk optimize length(row) in for-loop?
From: |
arnold |
Subject: |
Re: [bug-gawk] Does gawk optimize length(row) in for-loop? |
Date: |
Sat, 25 Mar 2017 12:13:18 -0600 |
User-agent: |
Heirloom mailx 12.4 7/29/08 |
Peng Yu <address@hidden> wrote:
> Hi, I have the following two code snippets. The first one takes the
> length() out of the loop. I am wondering whether gawk does any
> optimization for case 2 so that length() is only called once. Or
> length() will be called multiple times in case 2?
In case 2, length() will be called each time around the loop. It
would be a mistake to "optimize" that out since row could be
changed within the loop itself.
Arnold
> # code snippet 1
> nf = length(row)
> for(i=dat_col; i<=nf; ++i) {
> data[i] += row[i]
> }
>
> # code snippet 2
> for(i=dat_col; i<=length(row); ++i) {
> data[i] += row[i]
> }
>
> --
> Regards,
> Peng