CODEWITHSUNDEEP
bashshell
John Scott
John Scott

Reputation: 113

Compare two decimals and print similarities in Bash?

I'm working on a script that compares two very similar decimal numbers and I want the script to print the portion that the two numbers share. For example, suppose I have the numbers 42.86579 and 42.84578. Since both numbers have the 42.8 portion in common, I would like the script to output 42.8. How should I go about implementing this?

Upvotes: 1

Views: 54

Answers (2)

Eugene Yarmash
Eugene Yarmash

Reputation: 149971

You could search for the longest common prefix in two strings with sed:

$ x=42.86579
$ y=42.84578    
$ sed "s/\(.*\).* \1.*/\1/" <<< "$x $y"
42.8

Or slightly more concisely using GNU grep:

$ grep -Po '(.*).* \K\1' <<< "$x $y"
42.8

Upvotes: 3

Cyrus
Cyrus

Reputation: 88766

a=42.86579
b=42.84578

[[ ${a%.*} !=  ${b%.*} ]] && exit
for ((i=0;i<${#a};i++)); do 
  if [[ ${a:$i:1} == ${b:$i:1} ]]; then 
    echo -n ${a:$i:1}
  else
    break
  fi
done

Output:

42.8

See: Bash's parameter expansion

Upvotes: 2

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