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

#!/bin/bash

test="name"

array=('hello' 'world' 'my' 'yourname' 'name' 'is' 'perseus')
nelem=${#array[@]}
[[ "${array[0]} " =~ "$test " ]] || 
[[ "${array[@]:1:$((nelem-1))}" =~ " $test " ]] || 
[[ " ${array[$((nelem-1))]}" =~ " $test" ]] && 
echo "found $test" || echo "$test not found"

Just treat the expanded array as a string and check for a substring, but to isolate the first and last element to ensure they are not matched as part of a lesser-included substring, they must be tested separately.

Answer 2

With bash 4, the closest thing you can do is use associative arrays.

declare -A map
for name in hello world my name is perseus; do
  map["$name"]=1
done

...which does the exact same thing as:

declare -A map=( [hello]=1 [my]=1 [name]=1 [is]=1 [perseus]=1 )

...followed by:

tgt=henry
if [[ ${map["$tgt"]} ]] ; then
  : found
fi

Answer 3

array=('hello' 'world' 'my' 'name' 'is' 'perseus')
regex="^($(IFS=\|; echo "${array[*]}"))$"

test='henry'
[[ $test =~ $regex ]] && echo "found" || echo "not found"