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If then else for decimal numbers part2

 
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Top Forums UNIX for Dummies Questions & Answers If then else for decimal numbers part2
# 1  
Old 01-06-2011
If then else for decimal numbers part2
Hi,

I have a small problem with my script. I have everything in order but it doesnt seem to compare anything less than 1 correctly. If the input is more than 1, then the results is correct.

If the input is 0.xxx (anything) it returns erroneous results. Pls help

Code:
input=0.12

if [ $input -gt 0.1 ]; then
  echo "nok"
else
  echo "ok"
fi

Last edited by Scott; 01-08-2011 at 08:21 AM.. Reason: Please use code tags
# 2  
Old 01-06-2011
Please read the answers to your previous post:
https://www.unix.com/unix-dummies-que...numbers-2.html

Please also mention what Operating System and Shell you are using. It is important because there is normally no way to compare non-integers in Shell as such.
# 3  
Old 01-06-2011
Hi Methyl,

None of those worked. Yes i am using Unix shell script.

thanks.

---------- Post updated at 12:00 AM ---------- Previous update was at 12:00 AM ----------

OS using SUn Solaris and using sh
# 4  
Old 01-06-2011
You are probably using the default Bourne shell which does not support non-integers. Can you use the Korn shell i.e. ksh?
This User Gave Thanks to fpmurphy For This Post:
streddy
# 5  
Old 01-06-2011
Is see what you mean. The "bc" examples don't seem to work.

Assuming you can't find ksh93 on your computer, here is another method using "bc" which causes it to output either 9999 or 8888 according to the condition. The script contains test code to try various numbers.
Any approach which invokes an external program for each number could be slow for a large volume of calculations.

Code:
# Try various values
for input in "0.12" "0.1" "0.000001" "0.111111111111111" "75" "0" "2.222"
do
        reply=0
        reply=`echo "if (${input} > 0.1) 9999;if (${input} <= 0.1) 8888"|bc`
        echo "Input is: ${input}    Reply is: ${reply}"

        if [ ${reply} -eq 9999 ]
        then
                echo "${input} Greater than 0.1"
        else
                echo "${input} Not Greater than 0.1"
        fi
        echo ""
done

This User Gave Thanks to methyl For This Post:
streddy
# 6  
Old 01-07-2011
Guys,
thanks. it works with ksh. & Metyl thanx for the alternative solution. I will need that as well.

thanks

---------- Post updated 01-08-11 at 07:21 AM ---------- Previous update was 01-07-11 at 12:19 PM ----------

Hi,

I have got another issue now after changing it to Korn shell, it also accepts string values and compares.

How do i only declare the input=floatring numbers only?

pls help
# 7  
Old 01-08-2011
You can test the variable after the read, for example:
Code:
case $input in
  *[^0-9.+-]*) echo invalid input
esac

or
Code:
if [[ $input = *[^0-9.+-]* ]]; then
  echo invalid input
fi

recent ksh93:
Code:
if [[ ! $input =~ ^[+-]?[.0-9]+$ ]]; then
  echo invalid input
fi

 
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