Bash: Iterating through an array to get the value at each index

Question

The main goal of this program is to simulate the drawing of a card as many times as the user chooses and then print out a histogram using '*' to represent the number of hits on each card. However, the problem that I am having is retrieving the elements in each array and printing the stars that correlates with them. This is what I have so far:

timelimit=5
echo -e "How many trials would you like to run? \c"
read -t $timelimit trials

if [ ! -z "$trials" ]
then
    echo -e "\nWe will now run $trials trials"
else
    trials=10
    echo -e "\nWe will now run the default amount of trials: $trials"
fi

count=1
MAXCARD=53
declare -a CARDARRAY

while [ "$count" -le $trials ]
do
    card=$RANDOM
    let "card %= MAXCARD"
    let "CARDARRAY[$card] += 1"
    let "count += 1"
done  
echo ${CARDARRAY[@]}

for (( i=0; i<${#CARDARRAY[@]}; i++));
do
    #declare "temp"="${CARDARRAY[$i]}"
    #echo "$temp"
    #for (( j=0; j<temp; j++));
    #do
    #echo "*"
    #done
    echo "$i"
done

Obviously the last for loop is where I'm having trouble and is currently the latest attempt at printing the stars according to how many hits each card has.

choroba · Accepted Answer · 2016-12-02 06:33:40Z

2

You were pretty close. Here's how I'd paraphrase your script:

#!/bin/bash
timelimit=5
printf %s 'How many trials would you like to run? '
read -t $timelimit trials

if [[ ! -z $trials ]] ; then
    printf '\nWe will now run %d trials\n' $trials
else
    trials=10
    printf '\nWe will now run the default amount of trials: %d\n' $trials
fi

count=1
MAXCARD=53
declare -a CARDARRAY

while (( trials-- )) ; do
    (( CARDARRAY[RANDOM % MAXCARD] += 1 ))
done  

printf '%s\n' "${CARDARRAY[*]}"

for (( i=0 ; i<MAXCARD ; i++ )) ; do
    printf %02d: $i

    for (( j=0 ; j<${CARDARRAY[i]:-0} ; j++ )) ; do
        printf %s '*'
    done
    printf '\n' ''
done

You can use set -xv to see what bash is running at each step.

edited Dec 2, 2016 at 6:33

answered Dec 1, 2016 at 20:33

choroba

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1 Comment

Hotshot Over a year ago

Makes sense, coming from a language like C and Java, the formatting of bash is very new! Thank you for the help!

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