How to conditionally add elements to an array in shell script

Question

In the below shell script, I'm trying to conditionally add elements to an array which is syntactically incorrect when checked in shellcheck.

#!/bin/bash

echo "Hello World";
HH=1

ARR=(
    "a"
    "b"
    "c"
    if [ ${HH} = 1 ]; then
        "f"
    else
        "g"
    fi
    "d"
    "e"
)

for arr in "${ARR[@]}"; do
    echo "${arr}"
done

ShellCheck Error:

Line 6:
ARR=(
^-- SC1009 (info): The mentioned syntax error was in this variable assignment.
    ^-- SC1073 (error): Couldn't parse this array assignment. Fix to allow more checks.
 
Line 12:
    if [ ${HH} = 1 ]; then
                    ^-- SC1072 (error): Expected ) to close array assignment. Fix any mentioned problems and try again.

Answer 1

Keep it simple and set a variable to the value you want to use in the array:

if [[ "$HH" == 1 ]]; then
    foo="f"
else
    foo="g"
fi

ARR=(
    "a"
    "b"
    "c"
    "$foo"
    "d"
    "e"
)

Answer 2

How to conditionally add elements to an array in shell script

Here are some examples:

HH=1
ARR=(
    "a"
    "b"
    "c"
    "$(if [[ ${HH} == 1 ]]; then echo f; else echo g; fi)"
    "d"
    "e"
)

HH=1
lookup=([0]=g [1]=f)
ARR=(
    "a"
    "b"
    "c"
    "${lookup[HH]}"
    "d"
    "e"
)

HH=1
ARR=(
    "a"
    "b"
    "c"
    "d"
    "e"
)
if [[ ${HH} == 1 ]]; then
   ARR+=(f)
else
   ARR+=(g)
if

# insert element $3 at position $2 in array $1
array_insert() {
    local -n _arr="$1" || return 2
    _arr=("${_arr[@]::$2}" "${@:3}" "${_arr[@]:$2}")
}
HH=1
ARR=(
    "a"
    "b"
    "c"
    "d"
    "e"
)
if [[ ${HH} == 1 ]]; then
   array_insert ARR 3 f
else
   array_insert ARR 3 g
if

---

There is no need to do if [ ! ${#ARR[@]} -eq 0 ]; then. When array is empty, "${ARR[@]}" is nothing, so the loop will not run at all.