Awk - how to compare two numbers?

Question

This example works fine:

awk -v num1=5999 -v num2=5999  'BEGIN{ print (num2==num1) ? "equal" : "not equal" }'
equal

This example does not work well:

awk -v num1=59558711052462309110012 -v num2=59558711052462309110011 'BEGIN{ print (num2==num1) ? "equal" : "not equal" }'
equal

In the second example compared numbers are different. Why not print "not equal"?

@jw013 I noticed that too, but both examples shouldn't print the same result.
@jw013 these are just examples. jordanm is right that the two examples should not print the same result.

Stephane Chazelas · Accepted Answer · 2012-12-17 15:58:33Z

You're reaching the limit of the precision of awk numbers.

You could force the comparison to be a string comparison with:

awk -v num1=59558711052462309110012 -v num2=59558711052462309110011 '
  BEGIN{ print (num2""==num1) ? "equal" : "not equal" }'

(Here the concatenation with the empty string forces them to be considered as strings instead of numbers).

If you want to do numerical comparison, you'll have to use a tool that can work with arbitrary precision numbers like bc or python.

1 Answer