How to pass an associative array as argument to a function in Bash?

Question

How do you pass an associative array as an argument to a function? Is this possible in Bash?

The code below is not working as expected:

function iter         


        

Answer 1

yo:

 #!/bin/bash
   declare -A dict

   dict=(
    [ke]="va"
    [ys]="lu"
    [ye]="es" 
   )

   fun() {
     for i in $@; do
       echo $i
     done
    }

   fun ${dict[@]} # || ${dict[key]} || ${!dict[@] || ${dict[$1]} 

eZ

Answer 2

If you're using Bash 4.3 or newer, the cleanest way is to pass the associative array by name and then access it inside your function using a name reference with local -n. For example:

function foo {
    local -n data_ref=$1
    echo ${data_ref[a]} ${data_ref[b]}
}

declare -A data
data[a]="Fred Flintstone"
data[b]="Barney Rubble"
foo data

You don't have to use the _ref suffix; that's just what I picked here. You can call the reference anything you want so long as it's different from the original variable name (otherwise youll get a "circular name reference" error).

Answer 3

I had exactly the same problem last week and thought about it for quite a while.

It seems, that associative arrays can't be serialized or copied. There's a good Bash FAQ entry to associative arrays which explains them in detail. The last section gave me the following idea which works for me:

function print_array {
    # eval string into a new associative array
    eval "declare -A func_assoc_array="${1#*=}
    # proof that array was successfully created
    declare -p func_assoc_array
}

# declare an associative array
declare -A assoc_array=(["key1"]="value1" ["key2"]="value2")
# show associative array definition
declare -p assoc_array

# pass associative array in string form to function
print_array "$(declare -p assoc_array)" 

Answer 4

Based on Florian Feldhaus's solution:

# Bash 4+ only
function printAssocArray # ( assocArrayName ) 
{
    var=$(declare -p "$1")
    eval "declare -A _arr="${var#*=}
    for k in "${!_arr[@]}"; do
        echo "$k: ${_arr[$k]}"
    done

}

declare -A conf
conf[pou]=789
conf[mail]="ab\npo"
conf[doo]=456

printAssocArray "conf" 

The output will be:

doo: 456
pou: 789
mail: ab\npo

Answer 5

Here is a solution I came up with today using eval echo ... to do the indirection:

print_assoc_array() {
    local arr_keys="\${!$1[@]}" # \$ means we only substitute the $1
    local arr_val="\${$1[\"\$k\"]}"
    for k in $(eval echo $arr_keys); do #use eval echo to do the next substitution
        printf "%s: %s\n" "$k" "$(eval echo $arr_val)"
    done
}

declare -A my_arr
my_arr[abc]="123"
my_arr[def]="456"
print_assoc_array my_arr

Outputs on bash 4.3:

def: 456
abc: 123

Answer 6

You can only pass associative arrays by name.

It's better (more efficient) to pass regular arrays by name also.