Re: split a string into an array?

[Kerin Millar]

On Thu, 10 Mar 2022 21:25:53 -0600
Peng Yu <pengyu.ut@gmail.com> wrote:

> Hi,
> 
> I currently use the following method to split a string into an array
> using a separator (TAB is used in the example, but it could be other
> characters). Is this a robust way to do so? Is there any corner case
> that it will not handle correctly?
> 
> $ readarray -t -d $'\t' array <<< $'a\t\tb\tc'
> $ array[-1]=${array[-1]%$'\n'}
> $ declare -p array
> declare -a array=([0]="a" [1]="" [2]="b" [3]="c")

Here is a corner case:

$ readarray -t -d $'\t' array <<<''
$ array[-1]=${array[-1]%$'\n'}
$ declare -p array
declare -a array=([0]="")

You could do it this way instead:

$ readarray -t -d $'\t' array < <(printf %s $'a\t\tb\tc')
$ declare -p array
declare -a array=([0]="a" [1]="" [2]="b" [3]="c")
$ readarray -t -d $'\t' array < <(printf '')
$ declare -p array
declare -a array=()

> Also, when the separator is not a single character but rather a regex,
> is there a good way to split a string into an array? Thanks.

Only lightly tested ...

#!/bin/bash
re='[,|]'
str='foo|bar,baz|quux'
fields=()
while [[ $str =~ ($re) ]]; do
        value=${str%%"${BASH_REMATCH[1]}"*}
        fields+=("$value")
        str=${str:${#value} + ${#BASH_REMATCH[1]}}
done
fields+=("$str")
declare -p fields

The result is as follows.

declare -a fields=([0]="foo" [1]="bar" [2]="baz" [3]="quux")

-- 
Kerin Millar