simple scripting help please

kb100 · 08-18-2006, 07:24 AM

Hi there again. Wonder if anyone could help. How can you prompt a user if they would like to perform either, add, subtract, multiply or divide when imputting two numbers?

For example i ask a user for a number, then i ask the user if they would like to use an add, multiply, subtract or divide operation to calculate a second integer.

thanks

jlliagre · 08-18-2006, 07:33 AM

There are many ways, what have you in mind ?

kb100 · 08-18-2006, 07:36 AM

Sorry im trying to edit the message but my internet keeps stopping. What i want to do is ask the user to input an integer then i ask the user if they would like to use either an add, subtract, multiply or divide function. then i ask the user for a second integer and the result will appear.

thanks again

jlliagre · 08-18-2006, 07:38 AM

That looks just fine, which parts of this scenario have you trouble with ?

kb100 · 08-18-2006, 07:41 AM

i do not know how or what to use for the mathematics calculations.

jlliagre · 08-18-2006, 07:43 AM

The most portable is expr, eg:

Code:

expr $a + $b

will print the sum of a and b variables.

kb100 · 08-18-2006, 07:55 AM

How would i be able to give the choice to the user of what calculation he/she would like?

shall i give the user a keyboard choice, eg, if user presses the letter a the operation would add?

what will be the best way of doing this?

thanks for your reply.
how does everyone know how to do these things here??!!

BiThian · 08-18-2006, 07:57 AM

Well...probably they Googled for a bash tutorial

kb100 · 08-18-2006, 07:58 AM

alright mate

jlliagre · 08-18-2006, 08:19 AM

Quote:

Originally Posted by kb100

How would i be able to give the choice to the user of what calculation he/she would like?

shall i give the user a keyboard choice, eg, if user presses the letter a the operation would add?

That seem sensible.

Quote:

what will be the best way of doing this?

There is no "best way", and even if there is one, you should first focus on one that works.

Quote:

how does everyone know how to do these things here??!!

BeThian got it right, at least for the youngers of us.

kb100 · 08-18-2006, 08:22 AM

Hi there, figured it out and it all works. Thanks. but what symbol do you use for multiply? *?

thanks

unSpawn · 08-18-2006, 08:31 AM

How would i be able to give the choice to the user of what calculation he/she would like?
You could use "select" to present choices or just use a plain "case".

how does everyone know how to do these things here??!!
Find neat script or have problem. Look at other people's code.
How do they do that? How am I gonna fix this? Write own code.
Reinstall Linux ;-p and find out hard way need reading:
http://www.tldp.org/HOWTO/Bash-Prog-Intro-HOWTO.html then
http://www.tldp.org/LDP/Bash-Beginne...tml/index.html finally
http://www.tldp.org/LDP/abs/html/
Write own code. Reinstallation postponed by using "echo rm" instead of "rm" ;-p
Write some more. Typo scorches patch in side of computer casing.
Find out hard way need more examples. Search:
search LQ Bookmarks for bash and tutorial or guide
search LQ for "bash tutorial"
also see http://www.linuxquestions.org/questi...threadid=27957
and finally you can ask discuss things and ask questions ;-p

Difference is how much you want to leech vs learn.

jlliagre · 08-18-2006, 08:34 AM

Yes, multiply is a problem.

The operator is the expected * , but the shell expands it before expr has a chance to get it, so you need to escape it that way:

Code:

expr 2 \* 5

or if you use variables for the whole thing:

Code:

first=2
second=5
operand=*
eval expr $first \\$operand $second