shell script associate array value overwriting

Question

When I run the following shell script always I am getting the output as "grault" for any key. What would be the problem?

thanks!

#!/bin/bash

declare -a MYMAP                             
MYMAP=( [foo]=bar [baz]=quux [corge]=grault ) 

echo ${MYMAP[foo]}

echo ${MYMAP[baz]}

Run `declare -p MYMAP` to see its actual value. – Charles Duffy Feb 17 '18 at 01:06 — Charles Duffy, Feb 17 '18 at 01:06

score 3 · Answer 1 · answered Aug 13 '15 at 19:41

3

Create an associative array with -A:

declare -A MYMAP

See: help declare

answered Aug 13 '15 at 19:41

Cyrus

84,225
14
89
153

I am getting following error with -A associate-array.bash: line 2: declare: -A: invalid option declare: usage: declare [-afFirtx] [-p] [name[=value] ...] – G G Aug 13 '15 at 19:48
1

Sorry, your bash has no option `-A`. Add output of `echo $BASH_VERSION` – Cyrus Aug 13 '15 at 19:50
2

@GG You are probably on a Mac. Associative arrays were added in version 4. – John1024 Aug 13 '15 at 19:53
@GG: Take a look at [Create associative array in bash 3](http://stackoverflow.com/questions/11776468/create-associative-array-in-bash-3) – Cyrus Aug 13 '15 at 19:58
1

@GG Your welcome, of course, but it was Cyrus who correctly identified the issues. To thank him, I suggest that you accept and upvote his answer. For more information of Stackoverflow's peculiar customs, see: [What should I do when someone answers my question?](http://stackoverflow.com/help/someone-answer) – John1024 Aug 13 '15 at 20:39

score 1 · Answer 2 · answered Feb 17 '18 at 01:03

The other answer describes how to do it right, but here's the explanation of why your example behaves as it does.

declare -a creates an indexed array, which should only accept integers for the index. If you provide a string as the index, it will just disregard it and treat it as a 0! (I think this is a poor behavior, it should just give an error).

So this is what your code translated to:

declare -a MYMAP # create indexed array                           
MYMAP=( [0]=bar [0]=quux [0]=grault ) 

echo ${MYMAP[0]} # grault

echo ${MYMAP[0]} # grault

shell script associate array value overwriting

2 Answers2