如何在Bash中间接获取关联数组的键和值? [英] How to get the keys and values of an associative array indirectly in Bash?

问题描述

在Bash中，仅给出一个包含关联数组名称的变量，

In Bash, given only a variable that contains the name of an associative array,

$ declare -A dict=([abc]=125 [def]=456)
$ dictvar="dict"

我们如何检索关联数组的键和值?

how can we retrieve the keys and values of the associative array?

推荐答案

在Bash中，要通过间接获取关联数组的键，给定变量dictvar中的数组名称，则可以利用declare或(原始来源):

In Bash, to get keys of an associative array via indirection, given the name of the array in variable dictvar one can leverage declare or local (original source):

$ declare -a 'keys=("${!'"$dictvar"'[@]}")' # or 'local'

然后，获取值

$ for key in ${keys[@]}; do
$     value_var="${dictvar}[$key]"
$     echo "$key = ${!value_var}"
$ done

在此答案中建议使用eval的替代方法.

An alternative using eval is suggested in this answer.

根据此答案，在Bash 4.3+中，由于有了新的declare -n，此任务更容易实现可以将变量名解析"为实际变量.

According to this answer, in Bash 4.3+ this task is much easier to accomplish thanks to a new declare -n that can "resolve" a variable name into an actual variable.

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