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floating point numbers in if

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# 1  
Old 10-23-2009
floating point numbers in if
Code:
[root@mypbxadmin ~]# if [ 4.2 -gt 3.4 ]
> then
> echo "1"
> else
> echo "2"
> fi
-bash: [: 4.2: integer expression expected
2

How can i compare floating point numbers inside statement?
# 2  
Old 10-23-2009
Floating point numbers in test (a.k.a. [ ), not if
Quote:
Originally Posted by proactiveaditya
Code:
[root@mypbxadmin ~]# if [ 4.2 -gt 3.4 ]
> then
> echo "1"
> else
> echo "2"
> fi
-bash: [: 4.2: integer expression expected
2

How can i compare floating point numbers inside statement?

You don't. The test command cannot deal with floating-point numbers.

Convert them to integers or use awk:

Code:
if awk -v x=$1 -v y=$2 'BEGIN { exit (x > y) ? 0 : 1 }'
then
  echo 1
else
  echo 2
fi

# 3  
Old 10-23-2009
I am not an expert in awk. So i need more help. I have a variable named "VAR1" that stores a floating point number. I want to compare it with "12".
Code:
if [ $var1 -gt 12 ]
then
echo "1"
else echo "2"
fi

What should be the corresponding code in awk.

---------- Post updated at 04:32 PM ---------- Previous update was at 04:28 PM ----------

Should it be something like:
Code:
if awk -v x=$var1 -v y=12 'BEGIN { exit (x > y) ? 0 : 1 }'; then   echo 1; else   echo 2; fi

# 4  
Old 10-23-2009
or with 'bc':
Code:
#!/bin/ksh

a=1.72
b=1.71

if [ "$(echo "if (${a} > ${b}) 1" | bc)" -eq 1 ] ; then
   echo ">"
else
   echo "<"
fi

# 5  
Old 10-23-2009
Quote:
Originally Posted by proactiveaditya
I am not an expert in awk. So i need more help. I have a variable named "VAR1" that stores a floating point number. I want to compare it with "12".
Code:
if [ $var1 -gt 12 ]
then
echo "1"
else echo "2"
fi

What should be the corresponding code in awk.

For that, you don't need awk:

Code:
if [ $(( ${var1%.*} + ${var1#*.} )) -gt 12 ]
then
echo "1"
else echo "2"
fi

If the decimal portion of $var1 begins with 08 or 09, it'll have to be massaged.
# 6  
Old 10-23-2009
Code:
If the decimal portion of $var1 begins with 08 or 09, it'll have to be massaged.

Didn't understand this point clearly.
# 7  
Old 10-23-2009

Try it and see.
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