Mfcttrf

Imagine we have an array like this:

declare -a array=( "one" "two" "three" "four" "five" )

for i in "$all[@]"; do
 echo "$i"
done

And we can give an input from the user like this:

read -p "Enter a number: " number

I need something to check if the user input matches one of the elements of this array. If not, this should run:

echo "Try again: " 

This process should be repeated until the user input matches to one of the array elements.

You do not need to loop over the array to check whether a value belongs to it. Also, in this case I would use a recursive call of a function instead of another loop. As I understand correctly you are searching for something like this:

#!/bin/bash

array=( "one" "two" "three" "four" "five" )

function get_input() 
 read -p "$1: " number
 if [[ " $array[*] " == *" $number "* ]]
 then
 echo 'true';
 else
 get_input 'Try again' # a recursive call of the function
 fi


get_input 'Enter a number' # the initial call of the function

With the [[ test command we searing for exact match == between one string (the left side) and one regular expression (the right side).

• The expression " $array[*] " will expand our array as a string, surrounded by two spaces, thus each element (even the first and the last) will be surrounded by spaces - try echo '^'" $array[*] "'$'.




• The regular expression *" $number "* will match to any strung that consist of the value of the variable $number, surrounded by spaces, surrounded by no mater what other characters *.

We can perform such test by some other tools like grep (with suppressed stdout -q, and searching for exact match <...>). Here is one funny version:

#!/bin/bash

array=( "one" "two" "three" "four" "five" )

function get_input() get_input 'Try again'


get_input "Enter a number"

Probably all the other answers are more efficient than this one, but I think that this is more beginner-friendly:

declare -a all=( "one" "two" "three" "four" "five" )

read -p "Enter a number: " number

while true; do

 for i in "$all[@]"; do
 if [[ "$number" = "$i" ]]; then
 exit 0
 fi
 done

 read -p "Try again: " number

done

You can make the array into an associative array instead.

#!/bin/bash

declare -A array=([one]=1 [two]=1 [tree]=1 [four]=1 [five]=1)

m="Guess? "

while true; do 
 read -r -p "$m" i
 [[ $array[$i] == 1 ]] && break || m="Guess again? "
done 

echo "Good guess!"

#!/bin/bash

declare -a array=("one" "two" "three" "four" "five")

number="wrong"

while [[ ! "$array[@]" =~ "$number" ]]; do
 [[ "$number" != "wrong" ]] && echo "Incorrect"
 read -p "Insert number: " number
done