Negative number comparison using nawk on Linux


 
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# 1  
Old 09-02-2013
Negative number comparison using nawk on Linux

Hi All,

I am trying to compare two negative numbers using awk on linux.But it is giving me wrong result.Same code is working perfectly on solaris.

Code:
print ((0+new_price) < MIN_PRICE)

e.g If I try to compare -1.32(new_price) and -500(min_price) using "<" operator, output is 1 i.e true.

Where am I going wrong?

Thanks for your help in advance.
# 2  
Old 09-02-2013
Assuming that your comment is true and the code works as required then check 2 things...
Code:
echo "$SHELL"

And...
Code:
which awk

...and check that they are similar...
# 3  
Old 09-02-2013
That is odd, though I'm sure there's a perfectly reasonable explanation!

Have you made any efforts to debug the code?

i.e. it would be helpful if you showed where the variables new_price and MIN_PRICE (not the same as min_price!) are declared and set, as well as printing their values before the offending print statement.
# 4  
Old 09-02-2013
Quote:
Originally Posted by Rashmee
Hi All,

I am trying to compare two negative numbers using awk on linux.But it is giving me wrong result.Same code is working perfectly on solaris.

Code:
print ((0+new_price) < MIN_PRICE)

e.g If I try to compare -1.32(new_price) and -500(min_price) using "<" operator, output is 1 i.e true.

Where am I going wrong?

Thanks for your help in advance.
The most obvious explanation is that your solaris awk implementation, whatever it is, is performing a numerical comparison, while the linux awk implementation, whatever it is, is performing a string comparison (where -1.32 is indeed less, appears before -500 in a lexicographical sort).

To know which is correct (at least with respect to POSIX) would require seeing all of your code, which you neglected to post.

Add another +0 to the other operand to force numerical comparison, or, again, show us the entire script.

Regards,
Alister
This User Gave Thanks to alister For This Post:
# 5  
Old 09-02-2013
Curious, I tried this:
Code:
$ awk -v new_price=-1.32 -v MIN_PRICE=-500 'BEGIN{print ((0+new_price) < MIN_PRICE)}'
0

with every awk at my disposal and could not reproduce this. I did notice that you used MIN_PRICE in your script and min_price in your text about the value that you assigned to it. Could it be there is a mismatch (uppercase/lowercase) and therefore MIN_PRICE=0 would evaluate to 1
# 6  
Old 09-03-2013
Yes I did try to debug by printing values of variable and those were printing correct values. And I was using NEW_PRICE everywhere. Sorry for confusion created by mentioning new_price in my post.

My problem is now resolved, after I have added +0 to another operand i.e NEW_PRICE.

Thanks for your help.
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