[SOLVED] Printing array values

Faki · 04-28-2023, 10:38 AM

I am getting the following printed text. Why is bash complaining printing the array components ?

Code:

Anciator:
25uu failed numeric validation
-p Unrecognised Predicate
bash: 25uu: value too great for base (error token is "25uu")

Code:

  
if (( ${#anciator[@]} > 0 )); then
  printf '%s\n' "Anciator: ${anciator[@]}"
  for i in "${anciator[@]}"
  do
    printf '%s\n' "└── ${anciator[i]}"
  done
fi

michaelk · 04-28-2023, 10:58 AM

$i is each item i.e contents of each element of the array not the index.

Faki · 04-28-2023, 11:00 AM

What is the general way to print elements?

With

Code:

for i in "${anciator[@]}"

or via

Code:

for (( j=0; j<${length}; j++ ));
do
  printf "Current index %d with value %s\n" $j "${anciator[$j]}"
done

michaelk · 04-28-2023, 11:14 AM

Either way.

Faki · 04-28-2023, 12:38 PM

What is the way to print the index when using

Code:

for item in "${anciator[@]}"

michaelk · 04-28-2023, 01:17 PM

Code:

for i in "${!anciator[@]}"; do
  printf 'Current Index %s with value %s\n' "$i" "${anciator[i]}"
done

Faki · 04-28-2023, 01:50 PM

What would be the equivalent for a counter like so

Code:

for (( j = 0; j < ${#array[@]}; j++ ))
do
   printf "[%d] %s\n" $j "${anciator[$j]}"
done

I wonder whether using a counter as above could fail. The most secure way for printing seems to involve use of "${anciator[@]}" or "${!anciator[@]}", rather than the above.

pan64 · 04-28-2023, 02:39 PM

no, please do not use bash, it is not capable to do advanced handling of anything. It is nto meant to do that.

teckk · 04-28-2023, 02:39 PM

Code:

A=(One Two Three Four)
B=(Cat Dog Cow Bird)

#Alternate items from 2 arrays
for i in "${!A[@]}"; do
    echo -e ""${A[i]}"\n"${B[$i]}""
done

echo -e ''$_{1..50}'\b─'

for ((j = 0; j < ${#A[@]}; j++)); do
    echo -e ""${A[j]}"\n"${B[$j]}""
done

Edit:
Sorry, I put an i in there instead of a j

MadeInGermany · 04-29-2023, 12:43 AM

Looping over the array values is most simple if you only want the values.

If you want the indexes and the values then you must loop over the indexes.

In bash the normal arrays start with index 0.
And normally are contiguous, so the following works.

Code:

arr=( a b c d )
for (( j=0; j < ${#arr[@]}; j++ ))
do
   printf "[%d] %s\n" $j "${arr[$j]}"
done

But in bash you can delete an array element. (Arrays are "sparse".)

Code:

unset arr[1]

Then the array is no longer contiguous, and only the following works correctly:

Code:

for j in ${!arr[@]}
do
   printf "[%d] %s\n" $j "${arr[$j]}"
done

This is because the ${!arr[@]} generates the existing keys.
And of course "${arr[@]}" generates the existing values.

teckk · 04-29-2023, 06:49 AM

Interesting. I don't think that I noticed that before.

Code:

A=(One Two Three Four)

for ((j = 0; j < ${#A[@]}; j++)); do
    echo -e "${A[$j]}"
done

One
Two
Three
Four

unset A[1]

for ((j = 0; j < ${#A[@]}; j++)); do
    echo -e "${A[$j]}"
done

One

Three

for i in "${!A[@]}"; do
    echo -e "${A[$i]}"
done

One
Three
Four

Faki · 04-29-2023, 01:00 PM

Quote:

Originally Posted by pan64

no, please do not use bash, it is not capable to do advanced handling of anything. It is not meant to do that.

Have been thinking about your comment recently and plan to do some things in `perl`. Still for some of the things I currently have, an implementation in bash, even though crude, is good to have.

Faki · 04-29-2023, 01:13 PM

How is that the output is just this?

Code:

One

Three

teckk · 04-29-2023, 09:18 PM

#10 answers that.

Why don't you run some test yourself.

Code:

A=(One Two Three Four five Six Seven Eight)

for key in "${!A[@]}"; do 
    echo "Key "$key" is Value "${A[$key]}""
done

unset A[3]

for key in "${!A[@]}"; do 
    echo "Key "$key" is Value "${A[$key]}""
done



B=(One Two Three Four five Six Seven Eight)

for ((j = 0; j < ${#B[@]}; j++)); do
    echo "Key "$j" is Value "${B[$j]}""
done

unset B[3]

for ((j = 0; j < ${#B[@]}; j++)); do
    echo "Key "$j" is Value "${B[$j]}""
done

pan64 · 04-30-2023, 01:56 AM

Quote:

Originally Posted by Faki

How is that the output is just this?

Code:

One

Three

Code:

A=(One Two Three Four)
unset A[1]

set -xv

for ((j = 0; j < ${#A[@]}; j++)); # ${#A[@]} is the number of elements, it is now 3
do     
    echo -e "${A[$j]:-missing}"; 
done
+ (( j = 0 ))                     # j=0 initialization
+ (( j < 3 ))                     # j < ${#A[@]}, do the cycle 
+ echo -e One                     # print A[0]
One
+ (( j++ ))                       # increment j (j is now 1)
+ (( j < 3 ))                     # j < ${#A[@]}, do the cycle 
+ echo -e 'missing'               # print A[1]
missing                           # We have no A[1], it was unset
+ (( j++ ))                       # increment j (j is now 2)
+ (( j < 3 ))                     # j < ${#A[@]}, do the cycle 
+ echo -e Three                   # print A[2]
Three
+ (( j++ ))                       # increment j (j is now 3)
+ (( j < 3 ))                     # j < ${#A[@]} is false now, end of loop, exit
              # j = 3             # skipped