i have an array of zeros
declare -a MY_ARRAY=( $(for i in {1..100}; do echo 0; done) )
how to set, for example, 12-25th to "1"? i've tried:
MY_ARRAY[12..25]=1
MY_ARRAY[12:25]=1
MY_ARRAY[12-25]=1
all not working..
the range 12-25 will be variables obtain from another file. I am looking for a simple solution better not involve in looping
please help
You can use eval here, in this manner:
eval MY_ARRAY[{12..25}]=1\;
If you want to know what is being evaled, replace eval by echo.
Using eval is generally considered as a no-no. But this use of eval here should be completely safe.
On another note,
for i in {1..100}; do echo 0; done
can also be re-written as
printf '%.1s\n' 0{1..100}
EDIT: For start & end being stored in variables, this could work:
$ declare -i start=12
$ declare -i end=12
$ eval $(eval echo "MY_ARRAY[{$start..$end}]=1;")
But in that case, you should really use loops. This answer is only for demonstration/information.
declare -i start; declare -i end Plus, you should know, that brace expansion cannot contain variables. e.g. {$start..$end} will not work.Simple one-liner:-
for i in {12..25}; do MY_ARRAY[$i]=1; done
Refer page Arrays for more manipulation examples.
If the start & end values are stored in variables, the brace expansion would not work. In that case, you should use for loop like this:
$ declare -i start=12
$ declare -i end=25
$ for ((i=$start;i<=$end;i++)); do MY_ARRAY[$i]=1; done
declare -a MY_ARRAY=(
$(printf "%.2s" 0' '{1..11}) # 11 first zeroes
$(printf "%.2s" 1' '{12..25}) # 14 ones
$(printf "%.2s" 0' '{26..100}) # remaining zeroes
)
update
If the values 12 and 25 are in two variables, let's say, From and To:
declare -a MY_ARRAY=(
$( eval "{ printf %.2s 0_{1..$((From-1))};
printf %.2s 1_{$From..$To};
printf %.2s 0_{$((To+1))..100}; }" |
tr _ ' '
)
)
( ... )the index numbering starts in 0, unless you specify the index. e.g.( [3]="hello" ). Therefore the 12th element in yourMY_ARRAYis${MY_ARRAY[11]}.