CODEWITHSUNDEEP
arraysbash
chindit
chindit

Reputation: 1009

How to increment an associative array in Bash

I have this associative array:

lettres['A']=0
…(from 'A' to 'Z')…
lettres['Z']=0

My question is simple: How to take the value of one element and increment it? I have tried the following:

lettres[$char]=${lettres[$char]}++

But it fails, as the result is «0++++++++». How can I easily increment the value?

EDIT: More code:

while (( i++ < ${#word} )); do
    #$char current char
    char=$(expr substr "$word" $i 1)
    if [[ "${mot[@]}" =~ "${char} " || "${mot[${#mot[@]}-1]}" == "${char}" ]]; then
        #char is currently in array $mot -> skipping
        echo 'SKIPPING'
    else
        #Char is not in array $mot -> adding + incrementing lettres
        ((lettres[char]++))
        echo ${lettres[$char]}
        #Adding to $mot
        mot[${#mot[@]}]=$char
    fi
    echo "<$char>"
done

Upvotes: 3

Views: 5622

Answers (1)

Tom Fenech
Tom Fenech

Reputation: 74685

Using bash version 4 and up, this would work:

$ declare -A lettres
$ char=B
$ ((lettres[$char]++))
$ echo "${lettres['A']}"
0
$ echo "${lettres['B']}"
1

The (( )) force an arithmetic context, in which you can increment the value of the array element. Note that it is also recommended to use declare -A to guarantee maximum backward compatibility with standard indexed arrays.

Upvotes: 10

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