This tutorial will show how to make a simple calculator program that asks the user for two numbers. After the computer receives two numbers, the program will prompt the user to add, subtract, multiply or divide the two numbers. the program will display the answer and prompt the user to repeat the program or quit.
Input validation is used within this program. Input validation is used to check to see if the user entered the data correctly.
Code Download
QBT12.BAS
QB64 is a free download at www.qb64.org
QB64 Wiki & Manual is found at www.qb64.org/wiki/Main_Page
QBasic 1.1 is found within OldDOS.exe.
OldDos is a free download at download.microsoft.com/download/win95upg/tool_s/1.0/W95/EN-US/olddos.exe
On some web browsers, the Microsoft link does not work, because the download comes as an exe file.
A zip file of OldDOS can be found at www.pcxt-micro.com/download.html
QBasic 1.1 needs DOSBox to run on Windows Vista and greater, Mac, and Linux.
DosBox is a free download at www.dosbox.com
Free QB64/QBasic Code
QBasic.Net - www.qbasic.net
Pete's QBasic Site - www.petesqbsite.com/index.php
QB45 - qb45.org
Phatcode - games.phatcode.net