如何在Bash中迭代关联数组

Question

基于Bash脚本中的关联数组，我需要迭代它以获取键和值。

#!/bin/bash

declare -A array
array[foo]=bar
array[bar]=foo

我实际上不明白如何在使用for-in循环时获取密钥。

Answer 1

使用感叹号访问密钥：${!array[@]}，使用${array[@]}访问这些值。

您可以像这样迭代键/值对：

for i in "${!array[@]}"
do
  echo "key  : $i"
  echo "value: ${array[$i]}"
done

注意在for语句中使用变量周围的引号（加上使用@而不是*）。如果任何键包含空格，这是必要的。

另一个答案的混淆来自于你的问题包括键和值的“foo”和“bar”。

Answer 2

您可以使用${!array[@]}访问密钥：

bash-4.0$ echo "${!array[@]}"
foo bar

然后，迭代键/值对很容易：

for i in "${!array[@]}"
do
  echo "key :" $i
  echo "value:" ${array[$i]}
done

Answer 3

使用此更高阶函数来阻止pyramid of doom

foreach(){ 
  arr="$(declare -p $1)" ; eval "declare -A f="${arr#*=}; 
  for i in ${!f[@]}; do $2 "$i" "${f[$i]}"; done
}

例：

$ bar(){ echo "$1 -> $2"; }
$ declare -A foo["flap"]="three four" foo["flop"]="one two"
$ foreach foo bar
flap -> three four
flop -> one two

Answer 4

declare -a arr
echo "-------------------------------------"
echo "Here another example with arr numeric"
echo "-------------------------------------"
arr=( 10 200 3000 40000 500000 60 700 8000 90000 100000 )

echo -e "\n Elements in arr are:\n ${arr[0]} \n ${arr[1]} \n ${arr[2]} \n ${arr[3]} \n ${arr[4]} \n ${arr[5]} \n ${arr[6]} \n ${arr[7]} \n ${arr[8]} \n ${arr[9]}"

echo -e " \n Total elements in arr are : ${arr[*]} \n"

echo -e " \n Total lenght of arr is : ${#arr[@]} \n"

for (( i=0; i<10; i++ ))
do      echo "The value in position $i for arr is [ ${arr[i]} ]"
done

for (( j=0; j<10; j++ ))
do      echo "The length in element $j is ${#arr[j]}"
done

for z in "${!arr[@]}"
do      echo "The key ID is $z"
done
~