BASH: Adding numbers to an element of array-CodePudding

I'm learning shall scripting, and I wonder if there's any way to add numbers to an element of an array so that the number would be added to the element instead of appending it.

num=1
declare -A array
array[0] =$num
array[0] =$num
echo ${array[0]}

obviously, the result would be '11' instead of 2. I know this question might exists in the community, but I couldn't find it maybe because I don't know how to name the problem.

CodePudding user response：

You can use arithmetic context ((..)):

num=1
declare -A array
((array[0] =$num))
((array[0] =$num))
echo ${array[0]}

2

CodePudding user response：

Giving the array the integer attribute enables "bare" arithmetic:

num=1
declare -Ai array
array[0] =$num         
array[0] =num        # also works without expanding the variable
                     # because this is arithmetic evaluation
declare -p array

outputs

declare -Ai array=([0]="2" )

-A defines an associative array. -i also works with -a numerically-indexed arrays.