Understanding the Point of Declaring an Array in Bash

reno_rita

I'm trying to understand the point of ever explicitly declaring an array in bash. The course I'm doing states that you should create an array by using the command: $ declare -a ARRAYNAME I actually never knew about this command because I've never done my arrays like that. As an example, I wrote the script below and then deleted the 1st line of the file. The results were the same. Which begs the question, what's the actual point of ever using...

Originally asked by john smith on Stack Exchange (askubuntu) (CC BY-SA 4.0).

uphilltech

Great question — answering as the UphillTech team:

There is no reason I am aware of why you would have to declare it other than clarity and readibility of your code since declaring it is a clear indication to the next person who reads your code that "Hey, this variable will hold an indexed array". On the other hand, declaring associative arrays is indeed necessary. Unless explicitly declared as associative, arrays are treated as indexed in bash. Consider this example: #!/bin/bash for i in {a..c}; do badArray[$i]="foo $i" done declare -A goodArray for i in {a..c}; do goodArray[$i]="foo $i" done for i in {a..d}; do printf 'badArray value for key "%s" is: %s, goodArray value is: %s\n' \ "$i" "${badArray[$i]}" "${goodArray[$i]}" done echo "BAD:...

Full answer by terdon: https://askubuntu.stackexchange.com/a/1444694 (CC BY-SA 4.0).

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