A humble dc clone

rpn [-V] [--version] [-h] [--help]
    [-e scriptexpression] [--expression=scriptexpression]

This is a calculator that uses the reverse-polish notation (RPN). It stores the numbers in a stack and operates with the top ones until the desired result is reached.

For example the calculation (3 + 5) * 7 can be noted as 3 5 + 7 * in RPN.

See below for a complete set of commands.

Thanks to GMP, it supports arbitrary precision arithmetic.

rpn may be invoked with the following command-line options:

-V, --version

Print out the version of rpn that is being run and a copyright notice, then exit.

-h, --help

Print a usage message briefly summarizing these command-line options, then exit.

-e, --expression=script

Add the commands in script to the set of commands to be run while processing the input.

If any command-line parameters remain after processing the above, these parameters are interpreted as the names of input files to be processed. A file name of - refers to the standard input stream. The standard input will processed if no script files or expressions are specified.

This program depends on GNU MP library version 6 or above. It is available with the package libgmp-dev on Debian and derivative, as gmp-devel on Fedora or as gmp on Arch Linux.

$ make
$ ./rpn

p Prints the top value of the stack.

+ Pops two values off the stack, adds them and pushes the result on the stack.

- Pops two values off the stack, substracts the first from the second and pushes the result on the stack.

* Pops two values off the stack, multiplies them and pushes the result on the stack.

/ Pops two values off the stack, divids the first from the second and pushes the result on the stack.

% Pops two values off the stack, divids the first from the second and pushes the remainder on the stack.

~ Pops two values off the stack, divides the second one popped by the first one popped. The quotient is pushed first, and the remainder is pushed next.

^ Pops two values off the stack, use the first as the exponent and the second as the base and pushes the result on the stack.

v Pops one value, computes its square root, and pushes the result to the stack.

d Duplicates the top value of the stack.

r Swaps the two top values of the stack.

c Clears the stack.

f Prints the entire stack without modifying it.

This program is much more basic than dc and currently lacks some notable features like:

• decimal numbers
• memory registers
• conditionals and loops

Copyright 2016-2023 Pierre Faivre. This is free software, and may be redistributed under the terms specified in the LICENSE file.