Shell script adding float and integer

Question

I can't seem to debug the error in the computation of

case $code in
    ${menuCode[0]} )
        CBcost=$(echo "${menuItemsCost[0]} * $quantity" |bc) 
        sumOfCheeseBurgers=$(echo "$sumOfCheeseBurgers + $CBcost" |bc) 
    ;;

I need to be able to add all the sum of Burgers and store it to sumOfBurgers everytime the user enters Y for another transaction. However, I keep getting a (standard_in) 1: syntax error. How do I properly express sumOfBurgers=sumOfBurgers + CBcost?

declare -a menuItems=( 'Cheese Burger' 'Ham Burger' 'Spaghetti' 'Fried  Chicken' 'Softdrinks' )
declare -a menuItemsCost=( 25.00 20.00 24.00 30.00 15.00 )
declare -a menuCode=( CB HB SP FC SD )

clear

printf "MENU\n"
printf "=================================\n"
printf "CODE\tDESCRIPTION\t PRICE\t|\n"
echo   "================================="
printf "${menuCode[0]}  |\t${menuItems[0]}\t| ${menuItemsCost[0]} |\n"
printf "${menuCode[1]}  |\t${menuItems[1]}\t| ${menuItemsCost[1]} |\n"
printf "${menuCode[2]}  |\t${menuItems[2]}\t| ${menuItemsCost[2]} |\n"
printf "${menuCode[3]}  |\t${menuItems[3]}\t| ${menuItemsCost[3]} |\n"
printf "${menuCode[4]}  |\t${menuItems[4]}\t| ${menuItemsCost[4]} |\n"
printf "=================================\n"

choice="Y"
while [ $choice == "Y" ] 
    do
    printf "What's your order please? \n[Enter Code]: "
    read code
        while [ "$code" != "CB" ] && [ "$code" != "HB" ] && [ "$code" != "SP" ] && 
                [ "$code" != "FC" ] && [ "$code" != "SD" ]   
            do 
                printf "Please enter a valid ORDER code. \n[Enter Code]: " 
                    read code
                    code=$code 
        done

printf "Enter Quantity: "
    read quantity
printf "Do another transaction [Y/N]?: "
    read choice

case $code in
     ${menuCode[0]} )
        CBcost=$(echo "${menuItemsCost[0]} * $quantity" |bc) 
        sumOfCheeseBurgers=$(echo "$sumOfCheeseBurgers + $CBcost" |bc) 
    ;;
esac

done

printf "$sumOfCheeseBurgers\n"

Btw, for correct useage of printf see: help printf.

Cyrus
– Cyrus

2015-08-24 09:01:59 +00:00
Commented Aug 24, 2015 at 9:01 — Cyrus
– Cyrus, Commented Aug 24, 2015 at 9:01

Tom Fenech · Accepted Answer · 2015-08-24 09:27:45Z

1

You need to initialise sumOfCheeseBurgers before you use it here, otherwise it is an empty string which causes the syntax error from bc:

sumOfCheeseBurgers=$(echo "$sumOfCheeseBurgers + $CBcost" |bc)

Add the following line before the while loop:

sumOfCheeseBurgers=0

Or alternatively, as pointed out in the comments (thanks), you can use this syntax to assign a default value:

sumOfCheeseBurgers=$(echo "${sumOfCheeseBurgers-0} + $CBcost" |bc)

If you run your script like bash -x script.sh, you can see this error more clearly:

++ echo ' + 50.00'
++ bc

As you can see, the string being passed to bc is missing a value before the +.

As an aside, you should be using format specifiers with printf. For example:

printf "${menuCode[0]}  |\t${menuItems[0]}\t| ${menuItemsCost[0]} |\n"

should be something like this:

printf '%s  |\t%s\t| %s |\n' "${menuCode[0]}" "${menuItems[0]}" "${menuItemsCost[0]}"

This is the correct way to use printf as it prevents characters within your variables from being interpreted as escape characters (for example, newlines or tab characters).

edited Aug 24, 2015 at 9:27

answered Aug 24, 2015 at 9:19

Tom Fenech

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2 Comments

tripleee Over a year ago

... or use ${SumOfCheeseBurgers-0} in the echo.

heisenberg Over a year ago

Thanks, Tom. I appreciate the tips and the solution you provided. I've finished the program last night and got everything working fine. Some of the syntax in Shell is a bit different. I'll take note of the things I missed. Thanks again.

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