Category : BASIC Source Code
Archive   : LB09D.ZIP
Filename : SUMMARY.TXT

This file describes the many commands and functions of Liberty BASIC.
The format goes like this:


Command/Function Name and Syntax optional items in gray


Description:
a short, exact specification for the command/function

Usage:
an example of how to use the function command in a short
Liberty BASIC program fragment



Explore the included Liberty BASIC source files for more information.


See the section at the end of this file about commands for controlling
the spreadsheet, graphics, and text windows.


NOTE: This file is designed to be dumped to a printer with FF characters
to place each statement or function at the top of the next page.
For most, this is accomplished simply enough:

C:\LIBERTY>type summary.txt > lpt1:

or you could simply print this file from the Windows Notepad







ASC( n$ )

Description:

This function returns the ASCII value of the first character of string n$.

Usage:

print asc( "A" ) produces: 65

let name$ = "Tim"
firstLetter = asc(name$)
print firstLetter produces: 84

print asc( "" ) produces: 0

BEEP

Description:

This command simply rings the system bell, as in CTRL-G

Usage:

.
.
[loop]
input "Give me a number between 1 and 10?"; number
if number < 1 or number > 10 then beep : print "Out of range!" : goto [loop]
print "The square of "; number; " is "; number ^ 2
.
.


BUTTON #handle, label, return, corner, posx, posy

Description:

This statement lets you add buttons to windows that you open. The main
program window cannot have buttons added, but any window that you create
via the OPEN command can have as many buttons as you want. In this release
of Liberty BASIC, buttons cannot have graphic pictures on them, but only
text labels. This will be remedied in a future release.

Usage:

Before you actually OPEN the window, each button must be declared with a
BUTTON statement. Here is a brief description for each parameter as listed
above:

#handle - any valid file handle may be used. You must use the same handle
as will be used for the window that the button will belong to.

label - Type the label desired for the button here. Do not bound the word
with quotes, and do not use a string variable.

return - Again, use only one word and do not bound it with quotes or use a
string variable. If return is set to a valid branch label, then when
the button is pressed, execution will restart there (just as with
GOTO or GOSUB), but if return is not a valid branch label, then the
value of return is used as input to a specified variable (as in
input a$).

corner - UL, UR, LL, or LR specifies which corner of the window to anchor
the button to. For example, if LR is used, then the button will
appear in the lower right corner. UL = upper left, UR = upper
right, LL = lower left, and LR = lower right

posx, posy - These two parameters determine how to place the button relative to
the corner it has been anchored to. For example if corner is LR,
posx is 5, and posy is 5, then the button will be 5 pixels up and
left of the lower right corner. Another way to use posx & posy is
to use values less than one. For example, if corner is UL, posx
is .9, and posy is .9, then the button will be positioned 9/10th of
the distance of the window in both x and y from the upper left
corner (and thus appear to be anchored to the lower right corner).





BUTTON Continued

Here is a sample program:

' this button will be labeled Sample and will be located
' in the lower right corner. When it is pressed, program
' execution will transfer to [test]
button #graph, Sample, [test], LR, 5, 5

' this button will be labeled Example and will be located
' in the lower left corner. When it is pressed, the string
' "Example" will be returned.
button #graph, Example, Example, LL, 5, 5

' open a window for graphics
open "Button Sample" for graphics as #graph

' print a message in the window
print #graph, "\This is a test"

' get button input
[loop]
input b$
if b$ = "Example" then [example]
goto [loop]

' the Sample button has been pressed, ring the terminal bell
' and close the window
[test]
beep
close #graph
end

' The Example button has been pressed, close the window
' without ringing the bell
[example]
close #graph
end


CHR$( n )

Description:

Returns a one character long string, consisting of the character
represented on the ASCII table by the value n (0 - 255).

Usage:

' print each seperate word in text$ on its own line
text$ = "now is the time for all great men to rise"
for index = 1 to len(text$)
c$ = mid$(text$, index, 1)
' if c$ is a space, change it to a carraige return
if c$ = chr$(32) then c$ = chr$(13)
print c$ ;
next index Produces:

now
is
the
time
for
all
great
men
to
rise


CLOSE #handle

Description:

This command is used to close files and devices. This is the last step of
a file read and/or write, or to close graphic, spreadsheet, or other
windows when finished with them. If when execution of a program is
complete there are any files or devices left open, Liberty BASIC will
display a dialog informing you that it found it necessary to close the
opened files or devices. This is designed as an aid for you so that you
will be able to correct the problem. If on the other hand you choose to
terminate the program early (this is done by closing the program's main
window before the program finishes), then Liberty BASIC will close any open
files or devices without posting a notice to that effect.

Usage:

open "Graphic" for graphics as #gWindow ' open a graphics window
print #gWindow, "home" ' center the pen
print #gWindow, "down" ' put the pen down
for index = 1 to 100 ' loop 100 times
print #gWindow, "go "; index ' move the pen foreward
print #gWindow, "turn 63" ' turn 63 degrees
next index
input "Press 'Return'."; r$ ' this appears in main window
close #gWindow ' close graphic window


CLS

Description:

Clears the main program window of text and sets the cursor back at the
upper left hand corner. Useful for providing a break to seperate
different sections of a program functionally. Additionally, since the main
window doesn't actually discard past information on its own, the CLS
command can be used to reclaim memory from your program by forcing the main
window to dump old text.

Usage:

.
.
print "The total is: "; grandTotal
input "Press 'Return' to continue."; r$
cls
print "*** Enter Next Round of Figures ***"
.
.


CONFIRM string; responseVar

Description:

This statement opens a dialog box displaying the contents of string and
presenting two buttons marked 'Yes' and 'No'. When the selection is made,
the string "yes" is returned if 'Yes' is pressed, and the string "no" is
returned if 'No' is pressed. The result is placed in responseVar.

Usage:

[quit]

' bring up a confirmation box to be sure that
' the user want to quit
confirm "Are you sure you want to QUIT?"; answer$
if answer$ = "no" then [mainLoop]
end


COS( n )

Description:

Returns the cosine of the number n.

Usage:

.
.
for c = 1 to 45
print "The cosine of "; c; " is "; cos(c)
next c
.
.

Note:

See also SIN( ) and TAN( )


DATE$( )

Description:

Instead of adopting MBASIC's date$ variable, we decided to use a function
instead, figuring that this might give us additional flexibility later.
This function returns the current date in long format.

Usage:

print date$( )

Produces:

Feb 5, 1991


DIM array(size, size)

Description:

DIM sets the maximum size of an array. Any array can be dimensioned to
have as many elements as memory allows. If an array is not DIMensioned
explicitly, then the array will be limited to 10 elements, 0 to 9. Non
DIMensioned double subscript arrays will be limited to 100 elements 0 to 9
by 0 to 9.

Usage:

print "Please enter 10 names."
for index = 0 to 9
input names$ : name$(index) = name$
next index

The FOR . . . NEXT loop in this example is limited to a maximum value of 9
because the array names$( ) is not dimensioned, and therefore is limited to
10 elements. To remedy this problem, we can add a DIM statement, like so:

dim names$(20)
print "Please enter 20 names."
for index = 0 to 19
input names$ : names$(index) = name$
next index

Double subscripted arrays can store information more flexibly, like so:

dim customerInfo$(10, 5)
print "Please enter information for 10 customers."
for index = 0 to 9
input "Customer name >"; info$ : customerInfo$(index, 0) = info$
input "Address >"; info$ : customerInfo$(index, 1) = info$
input "City >"; info$ : customerInfo$(index, 2) = info$
input "State >"; info$ : customerInfo$(index, 3) = info$
input "Zip >"; info$ : customerInfo$(index, 4) = info$
next index


ELSE

See IF . . . THEN . . . ELSE


EOF(#handle)

Description:

Used to determine when reading from a sequential file whether the end of
the file has been reached. If so, -1 is returned, otherwise 0 is returned.

Usage:

open "testfile" for input as #1
if eof(#1) < 0 then [skipIt]
[loop]
input #1, text$
print text$
if eof(#1) = 0 then [loop]
[skipIt]
close #1


END

Description:

Used to immediately terminate execution of a program. If any files or
devices are still open (see CLOSE) when execution is terminated, then
Liberty BASIC will close them for you and present you with a dialog
expressing this fact. It is good programming practice to close files and
devices before terminating execution.

Note: The STOP statement is functionally identical to END and is
interchangable

Usage:

.
.
print "Preliminary Tests Complete."
[askAgain]
input "Would you like to continue (Y/N) ?"; yesOrNo$
yesOrNo$ = left$(yesOrNo$, 1)
if yesOrNo$ = "y" or yesOrNo$ = "Y" then [continueA]
ifYesOrNo$ = 'n" or yesOrNo$ = "N" then end
print "Please answer Y or N."
goto [askAgain]
[continueA]
.
.


FOR . . . NEXT

Description:

The FOR . . . NEXT looping construct provides a way to repeatedly execute
code a specific amount times. A starting and ending value are specified
like so:

for var = 1 to 10
{BASIC code}
next var

In this case, the {BASIC code} is executed 10 times, with var being 1 the
first time, 2 the second, and on through 10 the tenth time. Optionally
(and usually) var is used in some calculation(s) in the {BASIC code}.
For example if the {BASIC code} is print var ^ 2, then a list of squares
for var will be displayed upon execution.

The specified range could just as easily be 2 TO 20, instead of 1 TO 10,
but since the loop always counts +1 at a time, the first number must be
less than the second. The way around this limitation is to place STEP n
at the end of for FOR statement like so:

for index = 20 to 2 step -1
{BASIC code}
next index

This would look from 19 times returning values for index that start with
20 and end with 2. STEP can be used with both positive and and negative
numbers and it is not limited to integer values. For example:

for x = 0 to 1 step .01
print "The sine of "; x; " is "; sin(x)
next x




Note:

It is not recommended to pass control of a program out of a FOR . . . NEXT
loop using GOTO (GOSUB is acceptable). Liberty BASIC may behave unpredictably.


GOSUB label

Description:

GOSUB causes execution to proceed to the program code following the label
if it exists, using the form 'GOSUB label'. The label can be either a
traditional line number or a branch label in the format [???????] where the
?'s can be any upper/lowercase letter combination. Spaces and numbers are
not allowed.

Here are some valid branch labels: [mainMenu] [enterLimits] [repeatHere]
Here are some invalid branch labels: [enter limits] mainMenu [1moreTime]

After execution is transferred to the point of the branch label, then each
statement will be executed in normal fashion until a RETURN is encountered.
When this happens, execution is transferred back to the statement
immediately after the GOSUB. The section of code between a GOSUB and its
RETURN is known as a 'subroutine.' One purpose of a subroutine is to save
memory by having only one copy of code that is used many times throughout a
program.

Usage:

.
.
print "Do you want to continue?"
gosub [yesOrNo]
if answer$ = "N" then [quit]
print "Would you like to repeat the last sequence?"
gosub [yesOrNo]
if answer$ = "Y" then [repeat]
goto [generateNew]

[yesOrNo]
input answer$
answer$ = left$(answer$, 1)
if answer$ = "y" then answer$ = "Y"
if answer$ = "n" then answer$ = "N"
if answer$ = "Y" or answer$ = "N" then return
print "Please answer Y or N."
goto [yesOrNo]
.
.

You can see how using GOSUB [yesOrNo] in this case saves many lines of code
in this example. The subroutine [yesOrNo] could easily be used many other
times in such a hypothetical program, saving memory and reducing typing
time and effort. This reduces errors and increases productivity. See also
GOTO


GOTO label

Description:

GOTO causes Liberty BASIC to proceed to the program code following the label
if one exists, using the form 'GOTO label'. The label can be either a
traditional line number or a branch label in the format [???????] where the
?'s can be any upper/lowercase letter combination. Spaces and digits are
not allowed.

Here are some valid branch labels: [mainMenu] [enterLimits] [repeatHere]
Here are some invalid branch labels: [enter limits] mainMenu [1moreTime]

Usage:

.
.
[repeat]
.
.
[askAgain]
print "Make your selection (m, r, x)."
input selection$
if selection$ = "M" then goto [menu]
if selection$ = "R" then goto [repeat]
if selection$ = "X" then goto [exit]
goto [askAgain]
.
.
[menu]
print "Here is the main menu."
.
.
[exit]
print "Okay, bye."
end

Notes:

In the lines containing IF . . . THEN GOTO, the GOTO is optional.
The expression IF . . . THEN [menu] is just as valid as
IF . . . THEN GOTO [menu]. But in the line GOTO [askAgain], the GOTO
is required.

See also GOSUB


IF expression THEN expression(s)

Description:

The purpose of IF . . . THEN is to provide a mechanism for your computer
software to make decisions based on the data available. A decision-making
mechanism is used in very simple situations and can be used in combinations
to engineer solutions to problems of great complexity.

The expression (see above) is a boolean expression (meaning that it
evaluates to a true or false condition). In this expression we place the
logic of our decision-making process. For example, if we are writing a
inventory application, and we need to know when any item drops below a
certain level in inventory, then our decision-making logic might look like
this:

.
.
if level <= reorderLevel then expression(s)
next BASIC program line
.
.

The 'level <= reorderLevel' part of the above expression will evaluate to
either true or false. If the result was true, then the expression(s) part
of that line (consisting of a branch label or any valid BASIC statements)
will be executed. Otherwise execution will immediately begin at the next
BASIC program line.

The following are permitted:

if a < b then [lessThan]

This causes program execution to begin at branch label [lessThan]
if a is less than b

if sample < lowLimit or sample > highLimit then beep : print"Out of range!"

This causes the terminal bell to ring and the message Out of range! to be
displayed if sample is less than lowLimit or greater then highLimit.


IF expression THEN expression(s)1 ELSE expression(s)2

Description:

This extended form of IF . . . THEN adds expressiveness and simplifies
coding of some logical decision-making software. Here is an example of its
usefulness.

Consider:

[retry]
input"Please choose mode, (N)ovice or e(X)pert?"; mode$
if len(mode$) = 0 then print "Invalid entry! Retry" : goto [retry]
mode$ = left$(mode$, 1)
if instr("NnXx", mode$) = 0 then print "Invalid entry! Retry" : goto [retry]
if instr("Nn", mode$) > 0 then print "Novice mode" : goto [main]
print "eXpert mode"
[main]
print "Main Selection Menu"

Look at the two lines before the [main] branch label. The first of these
two lines is required to branch over the next line. These lines can be
shortened to one line as follows:

if instr("Nn",mode$)> 0 then print "Novice mode" else print "eXpert mode"

Some permitted forms are as follows:

if a < b then statement else statement
if a < b then [label] else statement
if a < b then statement else [label]
if a < b then statement : statement else statement
if a < b then statement else statement : statement
if a < b then statement : goto [label] else statement
if a < b then gosub [label1] else gosub [label2]

Any number of variations on these formats are permissible. The a < b
boolean expression is of course only a simple example chosen for convenience.
You must replace it with the correct expression to suit your problem.


INPUT #handle "string expression"; variableName

Description:

This command has three possible forms:

input var - stop and wait for user to enter data in the program's
main window and press the 'Return' key, then assign
the data entered to var.

input "enter data"; var - display the string "enter data" and then stop
and wait for user to enter data in the program's main window
and press 'Return', then assign the data entered to var.

input #name, var - or - input #name, var1, var2

- Get the next data item from the open file or device using handle named
#handle and assign the data to var. If no device or file exists that
uses the handle named #handle, then return an error. In the second case,
the next two data items are fetched and assigned to var1 and var2.

Usage:

'Display a text file
input "Please type a filename >"; filename$
open filename$ for input as #text
[loop]
if eof(#text) <> 0 then [quit]
input #text, item$
print item$
goto [loop]
[quit]
close #text
print "Done."
end


Note: In Liberty BASIC release 1.0, INPUT cannot be used to input data
directly into arrays, only into the simpler variables.

input a$(1) - is illegal
input string$ : a$(1) = string$ - use this instead

This shortcoming will be addressed in a future release. This should not be a
problem anyway if you will be checking the input for validity before
ultimately accepting it.

INPUT (continued)

Most versions of Microsoft BASIC implement INPUT to automatically place a
question mark on the display in front of the cursor when the user is prompted
for information like so:

input "Please enter the upper limit"; limit

produces:

Please enter the upper limit ? |

Liberty BASIC permits you the luxury of deciding for yourself whether the
question mark appears at all.

input "Please enter the upper limit :"; limit

produces:

Please enter the upper limit: |

and: input limit produces simply:

? |

In the simple form input limit, the question mark is inserted automatically,
but if you do specify a prompt, as in the above example, only the contents of
the prompt are displayed, and nothing more. If for some reason you wish to
input without a prompt and without a question mark, then the following will
achieve the desired effect:

input ""; limit

Additionally, in most Microsoft BASICs, if INPUT expects a numeric value and
a non numeric or string value is entered, the user will be faced with a
comment something like 'Redo From Start', and be expected to reenter.
Liberty BASIC does not automatically do this, but converts the entry to a zero
value and sets the variable accordingly. This is not considered a problem but
rather a language feature, allowing you to decide for yourself how your
program will respond to the situation.

One last note: In Liberty BASIC input prompt$; limit is also valid. Try:

prompt$ = "Please enter the upper limit:"
input prompt$; limit


INPUT$(#handle, items)

Description:

Permits the retrieval of a specified number of items from an open file or
device using #handle. If #handle does not refer to an open file or device
then an error will be reported.

Usage:

'read and display a file one character at a time
open "c:\autoexec.bat" for input as #1
[loop]
if eof(#1) <> 0 then [quit]
print input$(#1, 1);
goto [loop]
[quit]
close #1
end

For most devices (unlike disk files), one item does not refer a single
character, but INPUT$( ) may return items more than one character in length.
In most cases, use of INPUT #handle, varName works just as well or better for
reading devices.


INSTR(string1, string2, starting)

Description:

This function returns the position of string2 within string1. If string2
occurs more than once in string 1, then only the position of the leftmost
occurance will be returned. If starting is included, then the search for
string2 will begin at the position specified by starting.

Usage:

print instr("hello there", "lo")

produces: 4

print instr("greetings and meetings", "eetin")

produces: 3

print instr("greetings and meetings", "eetin", 5)

produces: 16

If string2 is not found in string1, or if string2 is not found after starting,
then INSTR( ) will return 0.

print instr("hello", "el", 3)

produces: 0

and so does:

print instr("hello", "bye") INT(number)

Description:

This function removes the fractional part of number, leaving only the whole
number part behind.

Usage:

[retry]
input "Enter an integer number>"; i
if i<>int(i) then bell: print i; " isn't an integer! Re-enter.": goto [retry]


LEFT$(string, number)

Description:

This function returns from string the specified number of characters starting
from the left. So if string is "hello there", and number is 5, then "hello"
would be the result.

Usage:


[retry]
input "Please enter a sentence>"; sentence$
if sentence$ = "" then [retry]
for i = 1 to len(sentence$)
print left$(sentence$, i)
next i

Produces:

Please enter a sentence>That's all folks!
T
Th
Tha
That
That'
That's
That's_
That's a
That's al
That's all
That's all_
That's all f
That's all fo
That's all fol
That's all folk
That's all folks
That's all folks!

Note:

If number is zero or less, then "" (an empty string) will be returned. If
the number is greater than the number of characters in string, then string
will be returned.

See also MID$( ) and RIGHT$( )


LEN( string )

Description:

This function returns the length in characters of string, which can be any
valid string expression.

Usage:

prompt "What is your name?"; yourName$
print "Your name is "; len(yourName$); " letters long"


LET assignment expression

Description:

LET is an optional prefix for any BASIC assignment expression. Most do leave
the word out of their programs, but some prefer to use it.

Usage:

Either is acceptable:

let name$ = "John"
or
name$ = "John"

Or yet again:

let c = sqr(a^2 + b^2)
or
c = sqr(a^2 + b^2)


MID$(string, index, number)

Description:

Permits the extraction of a sequence of characters from string starting at
index. If number is not specified, then all the characters from index to the
end of the string are returned. If number is specified, then only as many
characters as number specifies will be returned, starting from index.

Usage:

print mid$("greeting Earth creature", 10, 5)

Produces:

Earth

And:

string = "The quick brown fox jumped over the lazy dog"
for i = 1 to len(string$) step 5
print mid$(string$, i, 5)
next i

Produces:

The_q
uick_
brown
_fox_
jumpe
d_ove
r_the
_lazy
_dog


Note:

See also LEFT$( ) and RIGHT$( ) NEXT var

see FOR . . . NEXT


OPEN string FOR purpose AS #handle

Description:

This statement has many functions. It can be used to open disk files, or to
open windows of several kinds.

Disk files:

A typical OPEN used in disk I/O looks like this:

OPEN "\autoexec.bat" for input as #read

This example illustrates how we would open the autoexec.bat file for reading.
As you can see, string in this case is "\autoexec.bat", purpose is input, and
#handle is read.

string - this must be a valid pathname. If the file does not exist, it will
be created.

purpose - must be input, output, or random

#handle - use a unique descriptive word, but must start with a #.
This special handle is used to identify the open file in later
program statements

Windows:

A typical OPEN used in windows looks like this:

OPEN "Customer Statistics Chart" for graphics as #csc

This example illustrates how we would open a window for graphics. Once the
window is open, there are a wide range of commands that can be given to it
(see chapter ? - Liberty BASIC Graphics for more about this). As you can
see, string in this case is "Customer Statistics Chart", which is used as
the title of the window, purpose is graphics (open a window for graphics),
and the #handle is #csc (derived from Customer Statistics Chart), which will
be used as an identifier when sending commands to the window.

string - can be any valid BASIC string. used to label the window
purpose - there are a several of possibilities here:
graphics, spreadsheet, text
any of these can end in _fs, _nsbars (or other suffixes)
#handle - as above, must be a unique, descriptive word starting with #


Note: Any opened file or window must be closed before program execution is
finished. See CLOSE


PRINT #handle, pression ; expression(s) ;

Description:

This statement is used to send data to the main window, to a disk file, or
to other windows. A series of expressions can follow PRINT (there does not
need to be any expression at all), each seperated by a semicolon. Each
expression is displayed in sequence. If the data is being sent to a disk
file, or to a window, then #handle must be present.

PRINTing to a the main window:
When the expressions are displayed, then the cursor (that blinking vertical
bar | ) will move down to the next line, and the next time information is
sent to the window, it will be placed on the next line down. If you do not
want the cursor to move immediately to the next line, then add an additional
semicolor to the end of the list of expressions. This prevents the cursor
from being moved down a line when the expressions are displayed. The next
time data is displayed, it will be added onto the end of the line of data
displayed previously.

Usage: Produces:

print "hello world" hello world

print "hello "; hello world
print "world"

age = 23
print "Ed is "; age; " years old" Ed is 23 years old

When sending to a disk file and in regard to the use of the semicolon at the
end of the expression list, the rules are similar (only you don't see it
happen on the screen). When printing to a window, the expressions sent are
usually commands to the window (or requests for information from the window).
For more information, see chapter ?, Liberty BASIC Graphics.


PROMPT string; responseVar

Description:

The PROMPT statement opens a dialog box, displays string, and waits for the
user to type a response and press 'Return' (or press the OK or Cancel
button). The entered information is placed in responseVar. If Cancel is
pressed, then a string of zero length is returned. If responseVar is set to
some string value before PROMPT is executed, then that value will become the
'default' or suggested response. This means that when the dialog is opened,
the contents of responseVar will already be entered as a response for the
user, who then has the option to either type over that 'default' response, to
to press 'Return' and accept it.

Usage:

.
.
response$ = "C:"
prompt "Search on which Drive? A:, B:, or C:"; response$
[testResponse]
if response$ = "" then [cancelSearch]
if len(response$) = 2 and instr("A:B:C:", response$) > 0 then [search]
prompt "Unacceptable response. Please try again. A:, B:, or C:"; again$
goto [testResponse]

[search]
print "Starting search . . . "
.
.


REM comment

Description:

The REM statement is used to place comments inside of code to clearly
explain the purpose of each section of code. This is useful to both the
programmer who writes the code or to anyone who might later need to modify
the program. Use REM statements liberally. There is a shorthand way of
using REM, which is to use the ' (apostrophe) character in place of the word
REM. This is cleaner to look at, but use whichever you prefer. Unlike other
BASIC statements, with REM you cannot add another statement after it on the
same line using a colon ( : ) to seperate the statements. The rest of the
line becomes part of the REM statement.

Usage:

rem let's pretend that this is a comment for the next line
print "The mean average is "; meanAverage

Or:

' let's pretend that this is a comment for the next line
print "The strength of the quake was "; magnitude

This doesn't work:

rem thank the user : print "Thank you for using Super Stats!"

(even the print statement becomes part of the REM statement)


Note:

When using ' instead of REM at the end of a line, the statement seperator :
is not required to seperate the statement on that line from its comment.

For example:

print "Total dollar value: "; dollarValue : rem print the dollar value

Can also be stated:

print "Total dollar value: "; dollarValue ' print the dollar value

Notice that the : is not required in the second form.


RETURN

See GOSUB


RIGHT$(string, number)

Description:

Returns a sequence of characters from the right hand side of string using
number to determine how many characters to return. If number is 0,
then "" (an empty string) is returned. If number is greater than the number
of characters in string, then string will itself be returned.

Usage:

print right$("I'm right handed", 12)

Produces:

right handed

And:

print right$("hello world", 50)

Produces:

hello world

Note:

See also LEFT$( ) and MID$( )


RND(number)

Description:

This function returns a pseudo random number between 0 and 1. This can be
useful in writing games and some simulations. The particular formula used
in this release might more accurately be called an arbitrary number generator
(instead of random number generator), since if a distribution curve of the
output of this function were plotted, the results would be quite uneven.
Nevertheless, this function should prove more than adequate (especially for
game play).

In MBASIC it makes a difference what the value of parameter number is, but
in Liberty BASIC, it makes no difference. The function will always return
an arbitrary number between 0 and 1.

Usage:

' print ten numbers between one and ten
for a = 1 to 10
print int(rnd(1)*10) + 1
next a

SIN(number)

Description:

This function return the sine of number.

Usage:

.
.
for t = 1 to 45
print "The sine of "; t; " is "; sin(t)
next t
.
.

Note:

See also COS( ) and TAN( )


STR$(numericExpression)

Description:

This function returns a string expressing the result of numericExpression.
In MBASIC, this function would always return a string representation of the
expression and it would add a space in front of that string. For example
in MBASIC:


print len(str$(3.14))

Would produce the number 5 (a space followed by 3.14 for a total of 5
characters).

Liberty BASIC leaves it to you to decide whether you want that space or not.
If you don't want it, then you need not do anything at all, and if you do
want it, then this expression will produce the same result under Liberty
BASIC:

print len(" " + str$(3.14))

Usage:

.
.
[kids]
' use str$( ) to validate entry
input "How many children do you have?"; qtyKids
qtyKids$ = str$(qtyKids)
' if the entry contains a decimal point, then the response is no good
if instr(qtyKids$, ".") > 0 then print "Bad response. Reenter." : goto [kids]
.
.


TAN(number)

Description:

This function return the tangent of number.

Usage:

.
.
for t = 1 to 45
print "The tangent of "; t; " is "; tan(t)
next t
.
.

Note:

See also SIN( ) and COS( )
TIME$( )

Description:

This function returns a string representing the current time of the system
clock in 24 hour format. This function replaces the time$ variable used in
MBASIC. See also DATE$( ).

Usage:

.
.
' display the opening screen
print "Main selection screen Time now: "; time$( )
print
print "1. Add new record"
print "2. Modify existing record"
print "3. Delete record"
.
.


TRACE number

Description:

This statement sets the trace level for its application program. This is
only effective if the program is run using the Debug menu selection
(instead of RUN). If Run is used, then any TRACE statements are ignored by
the interpreter.

There are three trace levels: 0, 1, and 2. Here are the effects of these
levels:

0 = single step mode or STEP
1 = animated trace or WALK
2 = full speed no trace or RUN

When any Liberty BASIC program first starts under Debug mode, the trace
level is always initially 0. You can then click on any of the three buttons
(STEP, WALK, RUN) to determine what mode to continue in. When a TRACE
statement is encountered, the trace level is set accordingly, but you can
recover from this new trace level by clicking again on the desired button.

If you are having trouble debugging code at a certain spot, then you can add
a TRACE statement (usually level 0) just before that location, run in Debug
mode and then click on RUN. When the TRACE statement is reached, then the
debugger will kick in at that point.

Usage:

.
.
'Here is the trouble spot
trace 0 ' kick down to single step mode
for index = 1 to int(100*sin(index))
print #graph, "go "; index ; " "; int(100*cos(index))
next index
.
.


TRIM$(stringExpression)

Description:

This function removes any spaces from the start and end of the string in
stringExpression. This can be useful for cleaning up data entry among other
things.


Usage:

sentence$ = " Greetings "
print len(trim$(sentence$))

Produces:

9



USING(templateString, numericExpression)

Description:

This function formats numericExpression as a string using templateString.
The rules for the format are like those in MBASIC's PRINT USING statement,
but since USING( ) is a function, it can be used as part of a larger BASIC
expression instead of being useful only for output directly.


Usage:

' print a column of ten justified numbers
for a = 1 to 10
print using("####.##", rnd(1)*1000)
next a


VAL(stringExpression)

Description:

This function returns a numeric value for stringExpression is
stringExpression represents a valid numeric value or if it starts out as
one. If not, then zero is returned. This function lets your program take
string input from the user and carefully analyze it before turning it into
a numeric value if and when appropriate.

Usage:

print 2 * val("3.14") Produces: 6.28

print val("hello") Produces: 0

print val("3 blind mice") Produces: 3


WHILE expression . . . WEND

Description:

These two statements comprise the start and end of a control loop. Between
the WHILE and WEND statements place code (optionally) that will be executed
repeatedly while expression evaluates the same. Expression can be a boolean,
numeric, or string expression.

Usage:

' loop until midnight (go read a good book)
while time$ <> "00:00:00"
' some action performing code might be placed here
wend

Or:

' loop until a valid response is solicited
while val(age$) = 0
input "How old are you?"; age$
if val(age$) = 0 then print "Invalid response. Try again."
wend

Or:

' generate a list of ten non-consecutive random numbers
for count = 1 to 10
while random : random = int(rnd(1)*10)+1 : wend
print random
next count

WORD$( stringExpression, n )

Description:

This function returns the nth word in stringExpression. The leading and
trailing spaces are stripped from stringExpression and then it is broken
down into 'words' at the remaining spaces inside. If n is less than 1 or
greater than the number of words in stringExpression, then "" is returned.

Usage:

print word$("The quick brown fox jumped over the lazy dog", 5)

Produces:

jumped

And:

' display each word of sentence$ on its own line
sentence$ = "and many miles to go before I sleep."
tkn$ = "?"
while tkn$ <> ""
index = index + 1
tkn$ = word$(sentence$, index)
print tkn$
wend

Produces:

and
many
miles
to
go
before
I
sleep.

Summary of Window Device Commands
--------------------------------------------------------------------

In Liberty BASIC windows are treated like files, and we can refer
to anything in this class as a BASIC 'Device'. To open a window
we use the OPEN statement, and to close the window we use the
CLOSE statement. To control the window we 'print' to it, just as
we would print to a file. The commands are sent as strings to the
device. As a simple example, here we will open a graphics window,
center a pen (like a Logo turtle), and draw a simple spiral. We
will then pause by opening a simple dialog. When you confirm the
exit, we will close the window:

button #graph, Exit, [exit], LR, 5, 5 'window will have a button
open "Example" for graphics as #graph 'open graphics window
print #graph, "up" 'make sure pen is up
print #graph, "home" 'center the pen
print #graph, "down" 'make sure pen is down
for index = 1 to 30 'draw 30 spiral segments
print #graph, "go "; index 'go foreward 'index' places
print #graph, "turn 118" 'turn 118 degrees
next index 'loop back 30 times
print #graph, "flush" 'make the image 'stick'

[inputLoop]
input b$ : goto [inputLoop] 'wait for button press

[exit]
confirm "Close Window?"; answer$ 'dialog to confirm exit
if answer$ = "no" then [inputLoop] 'if answer$ = "no" loop back
close #graph

end


Here we used only a few of the commands available to us. Here are
three seperate lists, one for Graphics, one for Spreadsheet, and one
for Text windows:



GRAPHICS
------------------------------------------------------------------------


print #handle, "cls"

Clear the graphics window to white, erasing all drawn elements


print #handle, "fill COLOR"

Fill the window with COLOR. For a list of accepted colors see
the color command below.


print #handle, "home"

Center (or re-center) the pen in the window.


print #handle, "up"

Lift the pen up from the drawing surface. All go or goto commands
will only move to their new positions without drawing when the pen
is up.


print #handle, "down"

Just the opposite of up. This command causes lines to be drawn
when the pen is moved.


print #handle, "color COLOR"

Set the pen's color to be COLOR.

Here is a list of valid colors (in alphabetical order):

black, blue, brown, cyan, darkblue, darkcyan, darkgray,
darkgreen, darkpink, darkred, green, lightgray, palegray,
pink, red, white, yellow


print #handle, "goto X Y"

Move the pen to position X Y. Draw if the pen is down.


print #handle, "place X Y"

Position the pen at X Y. Do not draw even if the pen is down.


print #handle, "go D"

Go foreward D distance from the current position using the current
direction.


print #handle, "north"

Set the current direction to 270 (north). Zero degrees points to the
right (east), 90 points down (south), and 180 points left (west).


print #handle, "turn A"

Turn from the current direction using angle A and adding it to the
current direction. A can be positive or negative.


print #handle, "line X1 Y1 X2 Y2"

Draw a line from point X1 Y1 to point X2 Y2. If the pen is up, then
no line will be drawn, but the pen will be positioned at X2 Y2.


print #handle, "circle r"

Draw a circle whose center is the location of the pen and whose radius
is r.


print #handle, "posxy"

Return the current position of the pen in X & Y. This command must
be followed by:

input #handle, xVar, yVar

which will assign the pen's position to xVar & yVar


print #handle, "size S"

Set the size of the pen to S. The default is 1.


print #handle, "flush"

This ensures that the drawn graphics 'stick'. Make sure to issue this
command at the end of a drawing sequence to ensure that when the window
is resized or overlapped and redrawn, its image will be retained.


print #handle, "print"

Send the plotted image to the Windows Print Manager for output.


print #handle, "font facename width height"

Set the pen's font to the specified face, width and height. If an
exact match cannot be found, then Liberty BASIC will try to find a
close match, with size being of more prominance than face.


SPREADSHEET
----------------------------------------------------------------------

The spreadsheet used in Liberty BASIC is composed of 35 rows of 26
columns labeled from A to Z. The upper-left-most cell is A1 and
the lower-right-most cell is Z35. Each cell can contain one of three
types of data: string, number, or formula. To enter one of these
three types into any cell, simply move the selector over the cell on
the spreadsheet and begin typing. When done entering that cell's
contents, press 'Return'.

A string is entered by preceding it with an apostrophe '. Each cell
is 11 characters wide so if the string is longer than 11 characters
it will run into the next cell to its right.

A number is entered by entering its value, either an integer or a
floating point number.

A formula is a simple mathematical expression, using numbers (see
above) or cell references. The result of the formula is displayed
in the cell's position. Any arithmetic precedence is ignored, so
any formula is always evaluated from left to right and parenthesis
are not permitted (They aren't needed).

A sample formula to compute the average of 3 cells might be:
a1 + a2 + a3 / 3

The spreadsheet is a very special widget. Alone it is a very simple
but complete spreadsheet. But being able to send it commands and data
and to be able to read back data from it via Liberty BASIC makes it
a very powerful tool. For examples, see GRAPHER.BAS and CUSTOMER.BAS.

Modes:
The spreadsheet has two modes, manual and indirect. Manual mode means
that the operator can freely move about from cell to cell using the
arrow keys. He/she can also insert formulas in manual mode. Using
indirect mode, the user can only move between cells defined by the
controlling application, which also decides what type of data is
contained by each cell, either string or number.


Here are the commands:


print $handle, "manual"

The manual mode is the default setting. This mode permits the
user to move the cell selector wherever he/she wants and to
enter any of three data types into any cell: number, string, formula


print #handle, "format COLUMN right|fixed|none"

This command lets the application control formatting for an individual
column (COLUMN can be any letter A .. Z).

right - right justify column
fixed - assume 2 decimal places for numbers, and right justify also
none - left justify, default


print #handle, "indirect"

The indirect mode is the most useful when using a spreadsheet for
data entry. It enables the application to control which cells the
user has access to, and what kind of information they can contain.


print #handle, "cell ADDRESS CONTENTS"

Place CONTENTS into the cell at ADDRESS. ADDRESS can be any cell
address from A1 to Z35. The letter A to Z must be in uppercase.
CONTENTS can be any valid string, number or formula (see above).


print #handle, "user ADDRESS string|number"

Set aside the cell at ADDRESS (same rules apply as for ADDRESS in
command cell, above) as a user cell and specify the data it
contains to be either a string or a number (data entered will be
automatically converted to correct type). This command is only
effective when indirect mode is in effect (see above).


print #handle, "select ADDRESS"

Place the selector over the cell at ADDRESS (again, same rules).
It is important to place the selector over the first cell that
the user will edit.


print #handle, "result? ADDRESS"

Answer the result or value of the cell at ADDRESS (again, same
rules). If ADDRESS is not a valid cell address, then an empty
string will be returned. This command must be followed by:

input #handle, var$ (or input #handle, var if number expected)

which will leave the desired cell's contents in var$ (or var)


print #handle, "formula? ADDRESS"

Answer the formula of the cell at ADDRESS (again, same rules).
This command must also be followed with:

input #handle, var$ (should always be a string returned)

which will leave the desired cell's formula in var$


print #handle, "flush"

This commands forces the spreadsheet to display its most up to
date results.



TEXT WINDOW
------------------------------------------------------------------------

The text window works a little differently. Whatever you print to a
text window is displayed exactly as sent. The way to send commands to
a text window is to make the ! character the first character in the
string. For example:

open "Example" for text as #1 'open a text window
print #1, "Hello World" 'print Hello World in the window
print #1, "!font helv 16 37" 'change the text window's font
print #1, "!line 1" 'read line 1
input #1, string$
print "The first line of our text window is:"
print string$
input "Press 'Return'"; r$
close #1 'close the window


There are only four commands supported for text windows to date:


print #handle, "!cls"

Clears the text window of all text.


print #handle, "!font faceName width height"

Sets the font of the text window to the specified face of width and
height. If an exact match cannot be found, then Liberty BASIC will
try to match as closely as possible, with size figuring more
prominently than face in the match.


print #handle, "!line #"

Returns the text at line #. If # is less than 1 or greater than the
number of lines the text window contains, then "" (an empty string)
is returned. After this command is issued, it must be followed by:

input #handle, string$

which will assign the line's text to string$


print #handle, "!lines"

Returns the number of lines in the text window. After this command
is issued, it must be followed by:

input #handle, countVar

which will assign the line count to countVar




TIPS
------------------------------------------------------------------------

Once the techniques are mastered, the spreadsheet becomes a much better
mechanism for data entry than do plain INPUT statements in a BASIC
program's host window. This is especially true when many items need to
be entered. In this case, making the spreadsheet the control center
for your application might be a good idea. Just add buttons to the
spreadsheet to perform needed functions after data is entered.

Remember, any window can have buttons (except for the host window, which
is for some applications best kept minimized). Take advantage of this.
Release 0.9 does not have user definable pull down menus, but this will
not be a problem for registered users.

Don't forget to take advantage of the PROMPT and CONFIRM statements,
which borrow the syntax from the INPUT statement, but do their thing in
Windows dialogs. These simple statements can help make your programs
more Windows-like.

When running GRAPHER.BAS, try pulling down the command menu and
selecting Open. Two .ABC files will be offered. Load one of these
and click on the Graph button.