Loop over tuples in bash?

Question

Is it possible to loop over tuples in bash?

As an example, it would be great if the following worked:

for (i,j) in ((c,3), (e,5)); do echo \"$i and $         


        

Answer 1

c=('a' 'c')
n=(3    4 )

for i in $(seq 0 $((${#c[*]}-1)))
do
    echo ${c[i]} ${n[i]}
done

Might sometimes be more handy.

To explain the ugly part, as noted in the comments:

seq 0 2 produces the sequence of numbers 0 1 2. $(cmd) is command substitution, so for this example the output of seq 0 2, which is the number sequence. But what is the upper bound, the $((${#c[*]}-1))?

$((somthing)) is arithmetic expansion, so $((3+4)) is 7 etc. Our Expression is ${#c[*]}-1, so something - 1. Pretty simple, if we know what ${#c[*]} is.

c is an array, c[*] is just the whole array, ${#c[*]} is the size of the array which is 2 in our case. Now we roll everything back: for i in $(seq 0 $((${#c[*]}-1))) is for i in $(seq 0 $((2-1))) is for i in $(seq 0 1) is for i in 0 1. Because the last element in the array has an index which is the length of the Array - 1.