QBasic Coding for Beginners: Start Programming on MS-DOS 6.22

Welcome to QBasic, a beginner-friendly programming language that comes built into MS-DOS 6.22.To start QBasic, you'll need to access the MS-DOS command prompt, which looks like this.Simply type QBASIC at the prompt and press Enter to launch the programming environment.The QBasic interface will appear, featuring its distinctive blue background and menu-driven interface.QBasic provides quick access to common functions through the function keys, F1 through F10.The QBasic environment includes several helpful features for programming beginners.Before we dive into programming, let's review some essential MS-DOS commands you'll need to know.In QBasic, the PRINT command is your primary tool for displaying text and numbers on screen.Let's start with the most basic example - printing Hello World.Let's break down the syntax of the PRINT command.The PRINT command can also perform calculations directly.You can use multiple PRINT commands to display text on different lines.QBasic offers different ways to control line breaks in your output.Here's a practical example combining text and calculations in a simple receipt program.In QBasic, variables are used to store different types of data. Let's explore the various variable types.When naming variables, there are important rules we must follow to avoid errors.The INPUT command allows us to get data from the user. Here's how to use it with different variable types.When users enter incorrect data types, QBasic will show error messages and allow them to try again.Let's look at a complete program that uses variables and input commands to calculate someone's age.When we run this program and enter a birth year, it calculates and displays the age.In QBasic, IF-THEN statements allow your program to make decisions based on conditions.The basic structure starts with IF, followed by a condition, then THEN and the code to execute if true.You can also add an ELSE clause for when the condition is false.Let's see how this executes. When we input an age of 20...Since 20 is greater than 18, it executes the first PRINT statement.FOR-NEXT loops are used when you want to repeat code a specific number of times.The loop starts with FOR, specifying a counter variable and its range.Nested loops are loops within loops. They're useful for working with two-dimensional structures.This nested loop will create a three by three grid of asterisks.As the loops execute, each iteration adds another asterisk to the grid.In QBasic, saving your programs is essential. Programs are saved with the .BAS extension.To save your program, press F2 or use the File menu. Type a filename ending with .BASAfter entering the filename, press Enter to save your program.To load an existing program, press F3. You'll see a list of .BAS files in your directory.Once your program is loaded, press F5 to run it. QBasic will check for errors before execution.If your program has errors, QBasic will show an error message. Common errors include missing quotes or incorrect syntax.When debugging, check for common issues like matching quotes, correct variable names, and required keywords.After fixing the error, your program should run successfully.Press F5 again to run your corrected program.