MS-DOS Calculator

Have you ever needed to perform a quick calculation at the command prompt, well your prays have been answered. Below is the source code for an MS-DOS calculator that I created. It utilizes the MS-DOS command prompt's ability to perform basic math functions.

To create the CALC.BAT batch file, follow the instructions below:
- Open the Notepad, by typing "NOTEPAD.EXE" and press the Enter key in the Run... command.
- Select the text below and Copy it (Ctrl-C) from your browser window, then switch to the Notepad application and paste (Ctrl-V) the text into it.
- Save the file (Ctrl-S) as 'C:\WINDOWS\CALC.BAT'. (This allows you to run the command from anywhere).
- Then close the Notepad application.

---

@echo off
:: ----------------------------
:: Name:        MS-DOS Calculator
:: Description: Perform quick calculations from the MS-DOS prompt.
:: Author:      Jason Savitt
:: Version:     1.01
:: Web Site:    http://windowstipoftheday.blogspot.com/ also visit
::              http://ubergeek316.blogspot.com/
:: Notes:       - Requires Windows XP, 2003 or higher, although it may run
::                on Windows NT 4.0 and 2000 (not tested).
::              - Place the file in the %WinDir% (i.e.: C:\Windows)
::                to make it available from any where on your system.
:: ----------------------------

rem Creates the equation from the passed parameter from the command line.
if "%1" == "" goto DispHelp
set Equation=%1
:BuildEqu
shift
if "%1" == "" goto DispEqu
set Equation=%Equation%%1
goto BuildEqu
rem If the equation is empty, then it displays help

:DispEqu
echo.
rem Performs the equation and displays the results
set /a Results=%Equation%
echo %Equation% = %Results%
goto ExitProg

:DispHelp
rem Display help screen
echo.
echo The command line calculator supports the following operators, in 
echo decreasing order of precedence:
echo.
echo    ^(^)          - grouping
echo    ^! ^~ ^-       - unary operators
echo    ^* ^/ %%       - arithmetic operators
echo    ^+ ^-         - arithmetic operators
echo    ,           - expression separator
echo.
echo For example:
echo - calc 5+5
echo - calc (5-5)*10
echo - calc 20/5
goto ExitProg

:ExitProg
exit /b

---

To use the calculator, open the MS-DOS prompt then type "calc 5 * 5" (or whatever else you want) and press the Enter key. To get calculator Help, just type "calc" and press key Enter key.

---

The command line calculator supports the following operators, in
decreasing order of precedence:

   ()          - grouping
   ! ~ -       - unary operators
   * / %       - arithmetic operators
   + -         - arithmetic operators
   ,           - expression separator

For example:
- calc 5 + 5
- calc (5 - 5) * 10
- calc 20/5

---

Note: This batch has only been tested on Windows XP, although it should work on Windows NT4 or 2000. It will not work on Windows 95/98/ME, the MS-DOS prompt doesn't support the necessary functions need in order for it to work.