Simple Script Troubles (Please help)

JamesDoom · 05-04-2009, 12:24 PM

I've programmed in C++ for a while and recently decided to try to learn a bit of Linux and am just trying to do a simple little calculator and I'm having a bunch of trouble.

I'm skipping most of the stupid code that isn't necessary aka most of the echos and user prompts

but:
The user is prompted to enter two numbers NUM1 and NUM2, after which they have another prompt to select which operator to use.

Code:

echo -n "please enter the first number"
read NUM1

echo -n "Please enter the second number."
read NUM2

echo -n "Please enter which operator you would like to use"
read selection

case $selection in
m) let ans=NUM1*NUM2; echo $ans;;
*) echo -n "Please enter proper data"
esac

echo " "

the output gives me a '0' every time..why is that?

edit: this is only one of the cases because that's as far as I've gotten so far, it will be doing more.

forrestt · 05-04-2009, 12:51 PM

I'm not having any issue with your code. Perhaps something you didn't include is causing your problem.

Forrest

p.s. A cleaner way to prompt for variables is to use the -p option to read. Like this:

read -p "Please enter the first number: " NUM1

JamesDoom · 05-04-2009, 01:03 PM

Quote:

Originally Posted by forrestt

I'm not having any issue with your code. Perhaps something you didn't include is causing your problem.

Forrest

p.s. A cleaner way to prompt for variables is to use the -p option to read. Like this:

read -p "Please enter the first number: " NUM1

I'll post all the code in one second.

edit soon

Code:

echo -n "Which simple math equation would you like to use?"

echo  "Type the letter 'a' if you want addition."

echo -n "Type the letter 's' if you want subtraction."

echo -n "Type the letter 'd' if you want division."


echo -n "type the letter 'm' if you want multiplication."
echo -n ""

echo -n "please enter the first number: "
read NUM1

echo -n "Please enter the second number: "
read NUM2
echo " "
echo -n "Now please enter the selection from the top: "
read selection
case $selection in
m) let ANS = $NUM1*$NUM2; echo $ANS;;
d) let ANS=NUM1/NUM2 ; echo $ANS;;
a)let ANS=NUM1+NUM2 ; echo $ANS;;
*) echo "Proper data is required";;
esac

echo " "

error message:
./TestingScript: line 22: let: =: syntax error: operand expected (error token is "=")

forrestt · 05-04-2009, 01:21 PM

OK, I had to change

Code:

m) let ANS = $NUM1*$NUM2; echo $ANS;;

to

Code:

m) let ANS=$NUM1*$NUM2; echo $ANS;;

But everything else worked fine.

Here is how I would write this for a more readable script:

Code:

#!/bin/bash

echo "Which simple math equation would you like to use?"
echo "          'a' if you want addition."
echo "          's' if you want subtraction."
echo "          'd' if you want division."
echo "          'm' if you want multiplication."

read -p "please enter the first number: " NUM1

read -p "Please enter the second number: " NUM2

read -p "Now please enter the selection from the top: " selection

case $selection in
        m)
                let ANS=$NUM1*$NUM2
                ;;
        d)
                let ANS=NUM1/NUM2
                ;;
        a)
                let ANS=NUM1+NUM2
                ;;
        *)
                echo "Proper data is required"
                ;;
esac
echo $ANS

JamesDoom · 05-04-2009, 01:23 PM

I'll log back on linux and give it a try, I don't know why but no one else would respond on any other forums that I normally go to.

be right back.

JamesDoom · 05-04-2009, 01:41 PM

I got it to work all thanks to you.

Thank you so much for your help.

chrism01 · 05-05-2009, 02:28 AM

You may find this useful if you don't already have it: http://www.tldp.org/LDP/abs/html/