By using the Batch Scripting of command prompt one could even design a normal basic calculator that takes expressions and returns the result. Type the following script in notepad or any other text editor software:
@echo off :a echo ________Calculator________ echo. set /p expression= Enter expression to calculate: set /a ans=%expression% echo. echo = %ans% echo pause cls goto a
After writing the above text in a text editor, save the file with the extension “ .bat “. To run the program, simply double-click on the saved file, the program will open and the code will get executed in Command Prompt. It should look something like:
Code Explanation and Test Cases:
- @echo off — signals Command Prompt to not display the commands (code).
- : a — the signals starting point of a loop.
- echo — same as print/println/printf/etc. Displays the specified message as output to the screen.
- echo. — will output a blank line.
- set — used to set value against a variable.
- set /p expression — /p signals that this is prompt. “Expression” is just a variable name.
- set /a ans – /a signal that variable has a numerical value. “ans” is the variable name.
- %ans% — calls the variable “ans”
- pause — will pause/ stop the program flow until the user will press a key (any key) and continue the program flow only when the users press a key (any).
- cls – clears the screen
- goto a- signals to go to the start point of the loop, effectively looping our calculator program so it can take in and calculate new expression.
Program Test Cases:
- The program can handle simple expression calculations like:
- And it can also handle complex expressions, such as:
- The above program is calculating expressions by utilizing the calculator (that can perform simple arithmetic on 32-bit signed integers) that comes with Command Prompt.
- Since we are utilizing built-in calculator of Command Prompt, we can only perform following expression: + (addition), – (subtraction), * (multiplication), / (divide), % (modulo).