Set a parent shell's variable from a subshell

Question

How do I set a variable in the parent shell, from a subshell?

a=3
(a=4)
echo $a

Answer 1

If the problem is related to a while loop, one way to fix this is by using Process Substitution:

    var=0
    while read i;
    do
      # perform computations on $i
      ((var++))
    done < <(find . -type f -name "*.bin" -maxdepth 1)

as shown here: https://stackoverflow.com/a/13727116/2547445