Leegenux Blog

No man is an island

To learn about this topic, let’s start with a problem.

Snippet of code below is to be implemented:

a=13
b=12

# Please calculate their quotinent (a / b)

As much as I have learnt about arithmetic operations, there are 4 kinds of feasible solutions for BASH.

  • $(( expression )) gives the result of the calculation
  • Also you can do calculation using `expr expression`
  • To do calculation and assign the result directly, you can try this: ((result = $a + $b)) as well as ((result = a + b)), where result, a and b are all shell variables.
  • Using bc calculator with pipe.

For that problem, and with the help of the hints, we can provide 4 structurally different solutions respectively.

# Sol.1 
result=$((a / b))

# Sol.2
result=`expr a / b`

# Sol.3
((result = a / b))

# Sol.4
result=`echo "scale=16; $a/$b" | bc"`

If you try them all out, you will find that only the last solution gives float number as result. So one thing you should bear in mind is that built-in calculation of bash only does integers. To do float points, you must get the assistanse of external tools, in which bc is the one mostly referred to.

Built-in arithmetic operation in bash only does integers.

With this basic experience with arthmetic operation of bash and help of GOOGLE SEARCH, you can now solve more problems.

This article was last updated on days ago, and the information described in the article may have changed.