Re: (question) fast split/join of strings

[alex xmb sw ratchev]

very respectable great email mate

the set -f , ye i always missed it
i gotta train me that more in

the 1,2,,3 issue , id say thata valid cause ,, is literarly an empty field
a second sep seems me great
just as awk , one sep is for fields on a line , one is the per line sep

set -f ; ss=$'\1\2' ss=,: s1=${ss:0:1} s2=${ss:1:1} dat=1$s1\2$s1$s2\3$s1\4
IFS=$s2 d2=( $dat ) IFS=$s1
 for t in "${d2[@]}" ; do
d1=( $t )
declare -p d1
 done
declare -a d1=([0]="1" [1]="2")
declare -a d1=([0]="3" [1]="4")

plz what does 'local -' do , its newer to me
i forgot all about it already

thanks
greets

On Tuesday, September 17, 2024, Greg Wooledge <greg@wooledge.org> wrote:

> On Tue, Sep 17, 2024 at 16:07:58 +0200, alex xmb sw ratchev wrote:
> > savedifs=${IFS@A} savedifs=${savedifs:- unset -v IFS }
> > str=1,2,3 IFS=, arr=( $str ) joined=${arr[*]}
> > eval "$savedifs"
>
> Using unquoted $str in an array expansion to do the splitting has a
> couple drawbacks:
>
> 1) Globbing (filename expansion) is done unless you turn it off.
>
>     hobbit:~$ str=1,2,*.xml,4
>     hobbit:~$ IFS=, arr=( $str ); declare -p arr
>     declare -a arr=([0]="1" [1]="2" [2]="passwd.5.xml" [3]="4")
>
>    Workaround: set -f, but now you have an extra shell setting to
>    manage (do you do a set +f later, or do you wrap it in a function
>    and try to use "local -", or do you use a subshell, or do you simply
>    leave globbing disabled for the whole script...).
>
> 2) Pitfall 47 still applies.
>
>     hobbit:~$ bash
>     hobbit:~$ str=1,2,,4,
>     hobbit:~$ IFS=, arr=( $str ); declare -p arr
>     declare -a arr=([0]="1" [1]="2" [2]="" [3]="4")
>
>    Same workaround as all the others -- add an extra delimiter to the
>    end of the input string before splitting it.  If there is no empty
>    field at the end, then the extra delimiter gets eaten.  If there
>    is an empty field, then the extra delimiter preserves it before
>    being eaten.
>
>