How can I check if a string is in an array without iterating over the elements?

Question

Is there a way of checking if a string exists in an array of strings - without iterating through the array?

For example, given the script below, how I can correctly impl

Answer 1

Instead of iterating over the array elements it is possible to use parameter expansion to delete the specified string as an array item (for further information and examples see Messing with arrays in bash and Modify every element of a Bash array without looping).

(
set -f
export IFS=""

test='henry'
test='perseus'

array1=('hello' 'world' 'my' 'name' 'is' 'perseus')
#array1=('hello' 'world' 'my' 'name' 'is' 'perseusXXX' 'XXXperseus')

# removes empty string as array item due to IFS=""
array2=( ${array1[@]/#${test}/} )

n1=${#array1[@]}
n2=${#array2[@]}

echo "number of array1 items: ${n1}"
echo "number of array2 items: ${n2}"
echo "indices of array1: ${!array1[*]}"
echo "indices of array2: ${!array2[*]}"

echo 'array2:'
for ((i=0; i < ${#array2[@]}; i++)); do 
   echo "${i}: '${array2[${i}]}'"
done

if [[ $n1 -ne $n2 ]]; then
   echo "${test} is in array at least once! "
else
   echo "${test} is NOT in array! "
fi
)