Ubuntu – Bash pass both array and non-array parameter to function

bash

I want to create a function in bash that takes 2 parameters. One is simply a value and the other is an array. I would loop over the array and perform an operation using both the array element, and the other function parameter. It would be something like this (I don't know the proper syntax):

#!/bin/bash

function sumOverArray() {
   val=$1
   arr=("$@")
   for i in "${arr[@]}";
   do
      sum=$((i + val))
      echo "sum: $sum"
   done
}

array=(1 2 3)

sumOverArray 3 "${array[@]}"

Best Answer

Your code is almost complete. Just add shift after the assignment to $val, it will remove the first element from the $@ array.

...
val=$1
shift
arr=("$@")
...

Related Solutions

Ubuntu – how to pass array into function and updates to array are reflected outsite function

Several problems, in logical order of fixing:

Style (pet peeve)
With your ${...} statement in update_array(), the ${..} syntax to use a variable, not define it.

Example:
```
foo[0]=abc  # assigns 'abc' to foo[0]
```
Working around that the array name is stored in a variable.

Not working:
```
$1[0]=abc
```
Working:
```
declare -g "$1[0]=abc"  # -g arg is for a global variable
```
Passing an argument to update_array() should pass the variable name (foo in this case), not the contents of the array. foo[@] is nothing special, it is a completely normal string (in Bash).
Variable expansion with ${foo[@]} should be double-quoted.

Working version of the code is below:

update_array() {   
    declare -g "$1[0]=abc"
}

foo=(foo bar)

update_array foo

for i in "${foo[@]}"; do
    echo "$i"
done

## Following line added by me for further clarification
declare -p foo

which prints, correctly:

abc
bar
declare -a foo='([0]="abc" [1]="bar")'

Ubuntu – What’s the best way to transform a string into an associative array

I would do this just using bash itself:

#!/bin/bash
read -e -p 'Enter the string: ' post
declare -A myArr

while IFS='&' read name age; do
    myArr["${name##*=}"]="${age##*=}"
done <<<"$post"

printf 'NAME: %s, AGE: %s\n' "${!myArr[@]}" "${myArr[@]}"

Here is what i get in the output:

Enter the string: name=Foo Bar&age=40
NAME: Foo Bar, AGE: 40

The input string is spitted on & using IFS environmental variable
The name and age values are parsed using parameter expansion pattern ${var##*=}
You can get all keys using ${!myArr[@]} and all values using ${!myArr[@]}

In practice, I don't think you would just make an associative array of one element. If you have multiple elements, replace the last printf line with a simple for construct to loop over the keys:

for key in "${!myArr[@]}"; do
    printf 'NAME: %s, AGE: %s\n' "$key" "${myArr["$key"]}"
done

Best Answer

Related Solutions

Ubuntu – how to pass array into function and updates to array are reflected outsite function

Ubuntu – What’s the best way to transform a string into an associative array

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