Please enable JavaScript eh!

 ⌘ Web Mechanic ⌘ 

Array Subsets

Sometimes we only need to operate on a slice of an array - a set of contiguous elements.

Shell parameter expansion is our friend.

Using our Binary array from here, what can we do?

The syntax we need is ${string:<start>:<count>}.

#!/usr/bin/env bash
# arrays subset
clear
echo "bashMath2.sh"
echo
declare -a Binary # make Binary an array indexed by integers
Binary=(1 2 4 8 16 32 64 128)
for t in ${Binary[@]}; do
	echo $t
done
printf '%s' "The 6th element in Binary is: "
echo ${Binary[@]:5:1}
echo
echo "Now the 3rd, 4th and 5th elements: "
echo ${Binary[@]:2:3}
echo
echo "Rememember: string indexing starts at 0"
echo

bashMath2.sh

1
2
4
8
16
32
64
128
The 6th element in Binary is: 32

Now the 3rd, 4th and 5th elements:
4 8 16

Rememember: string indexing starts at 0