Liberty Basic, A natural Choice for a G Code Foundation

This is a great language to learn the basics of programming, sticking to the foundation, rather then going

into complicated higher level subjects too soon such as object oriented or memory allocation.   Because G

code is very similar to BASIC, and does not require to much higher level newer progrmaming techniques,

learning Liberty is a great way to get some inexpensive at home expierience.

             The best way to learn anything is to start practicing it. If you want to

learn  computer programming, you should start writing programs on your computer

as soon as possible.

You can learn to program by starting out with one of hundreds of programming

languages designed for novices, such as Pascal, LOGO, and SmallTalk.

But the most popular beginner’s programming language is still BASIC. BASIC

is simple enough to help you understand the concepts behind programming

yet powerful enough to enable you to create commercial-quality programs.

To help you in your quest to learn programming, this book comes with a

shareware copy of Liberty BASIC. As long as you’re running Windows 95/98/

Me/NT/2000/XP, you can run and use Liberty BASIC on your computer. Most

of this book provides examples in Liberty BASIC that you can type yourself.

If you have a Macintosh, you can’t run Liberty BASIC unless you buy a

special Windows emulation program such as VirtualPC from Microsoft

(at http://www.microsoft.com). As an alternative, you can use either True Basic

(www.truebasic.com) or Future Basic (www.stazsoftware.com). True

Basic, Future Basic, and Liberty BASIC all use BASIC language, so the sample

programs in this book designed for Liberty BASIC should run under both

True Basic and Future Basic with only minor modifications.

If for some odd reason you’re both technically knowledgeable enough to use

Linux, yet still want to learn how to program, you can download a free BASIC

interpreter, YABASIC (which stands for Yet Another BASIC), by visiting www.

yabasic.de.

Why Learn Liberty BASIC?

If you’re interested in learning to program, you may wonder, “Why not jump

right in and start learning C++ or Java?” (Then again, if you want to learn how

to swim, why not jump right into the ocean and start swimming with the

sharks?) Although you can start learning to program by using any language,

Liberty BASIC offers several advantages that you won’t find in other language

compilers.

Liberty BASIC is (almost) free

Liberty BASIC is a shareware program that you can evaluate for free until you

decide whether it’s worth paying for. That way, you can experiment with computer

programming without spending any money buying programs, such as

Visual C++ or JBuilder only to realize they may be too complicated and confusing

for you.

Liberty BASIC is easy

Liberty BASIC can teach you the fundamentals of programming so that you

can get real-life experience programming your own computer. Other programming

languages, such as C++ or Java, can force you to master needlessly complicated

topics, such as pointers, object-orientation, and memory allocation.

Rather than let these other programming languages bury you under an additional

layer of complexity that only gets in your way, learn Liberty BASIC.

Best of all, the BASIC programming language was specially designed to teach

novices how to program, so learning BASIC can teach you how programming

works. Once you learn the fundamentals of programming with Liberty BASIC,

you can apply your programming knowledge to help you better learn another

programming language, such as C++ or Java.

Liberty BASIC runs on Windows

When computers used to run the ancient operating system of MS-DOS,

Microsoft tossed in a free BASIC interpreter called QBASIC. Although you can

62 Part II: Learning Programming with Liberty BASIC

still run QBASIC in most versions of Windows (such as Windows 98 but not

Windows 2000), people have been screaming for a Windows-based version of

BASIC that they can use to teach themselves programming.

Because Microsoft has no intention of creating a Windows-based version

of QBASIC, the next alternative is to use Liberty BASIC. You can not only

write BASIC programs in Liberty BASIC on any computer that runs Microsoft

Windows, but you can also create real, honest-to-goodness Windows applications

using Liberty BASIC that you can sell or give away as well.

If you pay for the full version of Liberty BASIC, you can create real Windows

programs that you can sell to others. The shareware version of Liberty BASIC

(which comes with this book) allows you to write programs, but won’t allow

you to compile and distribute them to others.

You can start using Liberty BASIC today

Liberty BASIC comes with this book, so everyone reading this book can start

using it right away (unless, of course, you’re not using Windows). That makes

Liberty BASIC a natural learning tool to complement this book.

If trying to understand certain programming concepts confuses you, you can

quickly type a sample Liberty BASIC program and see for yourself exactly

how certain programming features work. By combining theory with hands-on

experience, this book and Liberty BASIC can help you pick up computer programming

in no time.

Installing Liberty BASIC

To install Liberty BASIC by using the CD that comes with this book, refer to

the installation instructions in the Appendix.

Because software changes so rapidly, a newer version of Liberty BASIC may

be available by the time you read this book. If you download a newer version

from the Liberty BASIC Web site (at http://www.libertybasic.com), you may need

to go through some extra steps to install Liberty BASIC on your computer.

If you download Liberty BASIC from the Liberty BASIC Web site, the file is

compressed in a self-extracting EXE file. To decompress this file, you need to

download and save this file somewhere on your hard disk, and then doubleclick

on the Liberty Basic EXE file (which has a cryptic name such as lb400win.

exe). When you double-click on the Liberty Basic EXE file, the Liberty Basic

installation program guides you, step-by-step, into installing Liberty Basic on

your computer.

Chapter 5: Getting Your Hands on a Real Language: Liberty BASIC 63

Loading Liberty BASIC

As you install Liberty BASIC, the program creates its own directory and adds

Liberty BASIC to your Program menu. To load Liberty BASIC, follow these

steps:

1. Click the Start button on the Windows taskbar.

The Start menu opens.

2. Choose Programs➪Liberty BASIC➪Liberty BASIC.

The Liberty BASIC program appears.

To make loading Liberty BASIC easier and faster, you can place a Liberty

BASIC icon on the Windows desktop.

To place a Liberty BASIC icon on your Windows desktop, follow these steps:

1. Right-click the Windows desktop.

A pop-up menu appears.

2. Choose New➪Shortcut.

A Create Shortcut dialog box appears.

3. Click Browse.

A Browse dialog box appears.

4. Find and click the Liberty BASIC program and then click Open.

You may need to change directories or drives to find the Liberty BASIC

program if it isn’t stored in the C:\Program Files\Liberty Basic directory.

After you click Open, the Create Shortcut dialog box appears again.

5. Click Next.

The Select a Title for the Program dialog box appears.

6. Type a name, such as Liberty BASIC, in the Select a Name for the

Shortcut text box and click Finish.

The Liberty BASIC icon appears on your desktop. The next time that you

want to load Liberty BASIC, just double-click this icon.

Your First Liberty BASIC Program

The Liberty BASIC editor is where you write, edit, and run your BASIC program.

To see the power of Liberty BASIC, type the following into the Liberty

BASIC editor:

64 Part II: Learning Programming with Liberty BASIC

PRINT “This BASIC program mimics a really bad boss.”

PRINT

PRINT “What is your name?”

INPUT Name$

PRINT “Hello “ + Name$ + “. You’re fired! Have a nice day.”

END

Liberty BASIC, like most versions of BASIC, doesn’t care whether you type

commands in uppercase, lowercase, or a mixture of both. Most programmers,

however, like to use all uppercase to identify all the BASIC commands that

they use in a program.

Unlike a word processor, the Liberty BASIC editor doesn’t wrap words from

one line to the other, which means that you can keep typing all the way to the

far right until your text scrolls out of view.

This program tells the computer to perform the following tasks:

1. The first line prints the message This BASIC program mimics a

really bad boss. on-screen.

2. The second line prints (adds) a blank line directly underneath the

message.

3. The third line prints What is your name? on-screen.

4. The fourth line displays a question mark (?) as a prompt and waits for

the user to type a name. As soon as the user presses the Enter key, the

BASIC program stores whatever the user types into a temporary

memory location that it identifies as Name$.

5. The fifth line prints the message “Hello (following it by the name that

the user types in the fourth line). You’re fired! Have a nice

day.” The plus sign (+) tells Liberty BASIC to add the word “Hello”

with the words that it stores in Name$.

6. The sixth line tells the computer that this is the end of the program.

Running a Liberty BASIC program

After you finish typing a BASIC program, press Shift+F5 or choose Run➪Run

from the Liberty BASIC menu bar to run the program. Figure 5-1 shows what

the BASIC program from the preceding section looks like when run on Liberty

BASIC.

As you run this program, Liberty BASIC displays the text in a window that it

calls the main window. You can use the menu bar in the main window to print

or save any text that appears in the main window.

Chapter 5: Getting Your Hands on a Real Language: Liberty BASIC 65

Saving a Liberty BASIC program

Although you can type your Liberty BASIC programs over and over whenever

you want to run them, saving your program to a hard drive or floppy disk is

much easier. Then you can load and edit the program later.

To save a program, follow these steps:

1. Choose File➪Save from the Liberty BASIC menu bar, or click the Save

File icon on the Liberty Basic toolbar as shown in Figure 5-2.

The Save As dialog box appears.

2. Type a name for your file in the Filename text box.

You may want to change folders or drives to store your Liberty BASIC file.

3. Click OK.

Liberty BASIC automatically adds a BAS file extension to Liberty BASIC programs

that you save. Unless you have a good reason to change this file extension,

use the BAS extension to help you identify your Liberty BASIC programs

from any other files stored on your computer.

Main window

Figure 5-1:

Running

your first

Liberty

BASIC

program.

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