I'm running into an issue with two different ways of getting the length of an array in a bash script. One method works perfectly, while the other just doesn't seem to do anything right in the script. I've tested both methods in the command prompt and they work fine there. Here are the two methods: the first one is `len="$(echo "${n_list[@]}" | wc -w)"`, which gives me the correct length, and the second one is `len="${#n_list[@]}"`, which doesn't work as expected. Why is there a difference?
3 Answers
It sounds like the way you initialize `n_list` might be causing issues. If you generate the numbers using a function that outputs them line by line, it could create an array incorrectly. You might also want to check what `which bash` returns to ensure your script runs in the same shell version as your command line tests.
Try this simple test to troubleshoot:
```bash
printf '(%q)n' "${n_list[@]}"
```
This will display each element in the array separately on a new line. It can help you verify if your array is being set up correctly.
The difference you're seeing is mainly due to how these commands interpret the contents of the array. When you use `wc -w`, it counts the number of words, meaning it counts elements based on spaces. On the other hand, `${#n_list[@]}` gives you the number of elements in the array itself, which may not be what you expect if there are spaces or newlines in your inputs. Check how you're populating `n_list`—that could be the key!
Exactly! If `n_list` is getting its values from commands that add numbers on new lines, you might want to print it out and see what's actually going in there. Sometimes, using `echo` to check can reveal hidden spaces or formatting issues.