bcalc

A calculator written in pure bash.

I even managed to write a lexer for the argument input, allowing you to do 1+1 instead of 1 + 1.

I made sure to thouroughly comment the script, feel free to check it out if you're interested!

Syntax

• () = do this first and replace with the done math
• ^ = exponent
• * = multiplication
• % = division with remainder
• / = division
• + = addition
• - = subtraction

What's supported

• Basic math operations
• PEMDAS
• Whole numbers

Examples:

$ ./bcalc 100*50
5,000

$ ./bcalc 1000/100
10

$ ./bcalc 100+100+100+100
400

$ ./bcalc 9-1-2-3-4
-1

$ ./bcalc '(100+50)/2'
75

$ ./bcalc '(100+50)+2^2'
154

There is also a debug mode implemented, which is useful for when the output seems wrong. Here is an example:

$ ./bcalc 100-50 --debug
final_array = 1 0 0 - 5 0
mn = 1 0 0
numbers = 100
numbers = 50
number_array[0] = 100
operation_array[0] = -
operation_array[1] =
number_array[1] = 50
operation_array[0] = -
operation_array[1] =
number_array[2] =
operation_array[0] = -
operation_array[1] =
number_count = 2
operation_count = 1
calculation = 100-50
50

• final_array = the comlpete array of characters that were inputted
• mn = short for multi-digit number
• number_array = an array of all the numbers
• operation_array = an array of all the operations
• calculation = the calculation to be used

TODO

• Better formatted ouput (perhaps 1,000,000 instead of 1000000 for example)
• No hard limit on number/operator count
• Support decimals apparently this is not possible in pure bash
• Support PEMDAS (bash had already mostly supported PEMDAS, just needed to support for parenthesis)
  • Parenthesis
  • Exponents
  • Multiplication
  • Division
  • Addition
  • Subtraction

Off-topic from this calculator:

I feel like the work I would put into the lexer for this calculator,
can be adapted into a framework for creating custom languages in BASH.

I'm definitely going to look into this after I've done more work on the calculator.