ABS( n )

Description:

  This function returns  | n |  (the absolute value of n).

Usage:

  print abs( -5)                   produces:  5

  print abs( 6 - 13 )            produces: 7



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



ACS( n )

Description:

  Returns the arc-cosine of the number n.

Usage:

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

Note:

  See also COS( )



ASN( n )

Description:

  Returns the arcsine of the number n.

Usage:

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

Note:

  See also SIN( )



ATN( n )

Description:

  Returns the arc-tangent of the number n.

Usage:

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

Note:

  See also TAN( )



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
  .
  .




BMPBUTTON #handle, filespec, return, corner, posx, posy

Description:

  This statement lets you add bitmapped 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.  

Usage:

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

#handle - You must use the same handle that will be used for the window that
     the button will belong to.

filespec   - The full pathname of the *.bmp file containing the bitmap for the
      button you are creating.  The button will be the same size as the
      bitmap.

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). 

  A collection of button *.bmp has been included with Liberty BASIC, including
  blanks.  Windows Paint can be used to edit and make buttons for Liberty BASIC.

  Program execution must be halted at an input statement in order for a button
  press to be read and acted upon.


  See also: BUTTON, MENU



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.

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 - You must use the same handle that 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). 

  Program execution must be halted at an input statement in order for a button
  press to be read and acted upon.  See below.



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, Bell, [bell], 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, Quit, [quit], 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"
    print #graph, "flush"

  ' get button input
[loop]
  input b$   ' stop and wait for a button to be pressed
  if b$ = "Example" then [example]
  goto [loop]

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

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



  See also:  BMPBUTTON, MENU



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 wants 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

Or you can assign a variable the result:

  d$ = date$( )



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]
  .
  .



EXP( n )

Description:

  This function returns e ^ n,   e being 2.7182818 . . .

Usage:

  print exp( 5 )              produces:  148.41315



FIELD #handle, # as varName, # as varName, . . . 

Description:

  FIELD is used with an OPEN "filename.ext" for random as #handle
  statement to specify the fields of data in each record of the opened file.  For
  example in this program FIELD sets up 6 fields of data, each with an
  appropriate length, and associates each with a string variable that holds the
  data to be stored in that field:

  open "custdata.001" for random as #cust len = 70   ' open a random access file
  field #cust, 20 as name$, 20 as street$, 15 as city$, 2 as state$, 10 as zip$, 3 as age

[inputLoop] 
  input "Name >"; name$
  input "Street >"; street$
  input "City >"; city$
  input "State >"; state$
  input "Zip Code >"; zip$
  input "Age >"; age

  confirm "Is this entry correct?"; yesNo$   ' ask if the data is entered correctly
  if  yesNo$ = "no" then [inputLoop]

  recNumber = recNumber + 1   ' add 1 to the record # and put the record
  put #cust, recNumber

  confirm "Enter more records?"; yesNo$   ' ask whether to enter more records
  if yesNo$ = "yes" then [inputLoop]

  close #cust   ' end of program, close file
  end

Notice that Liberty BASIC permits the use of numeric variables in FIELD
(eg. age), and it allows you to PUT and GET with both string and numeric
variables, automatically, without needing LSET, RSET, MKI$, MKS$, MKD$,
CVI, CVS, & CVD that are required with Microsoft BASICs.

Note: See also PUT and GET



FILEDIALOG titleString, templateString, receiverVar$

Description:

  This command opens a file dialog box.  The titleString is used to
  label the dialog box.  The templateString is used as a filter to
  list only files matching a wildcard, or to place a full suggested
  filename.

 The box lets you navigate around the directory structure,
  looking at files that have a specific extension.  You can then select
  one, and the resulting full path specification will be placed into
  receiverVar$, above.

  The following example would produce the dialog box below:

    filedialog "test it", "*.txt", fileName$



If then summary.txt were selected, and OK clicked, then program
execution would resume after placing the string "c:\liberty\summary.txt"
into fileName$.

If on the other hand Cancel were clicked, then an empty string
would be placed into fileName$.  Program execution would then resume.

Look at the program grapher1.bas for a practical application of 
this command.



FOR . . . NEXT

Description:

  The FOR . . . NEXT looping construct provides a way to repeatedly execute 
  code a specific amount of 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 loop 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.  For example:

  for index = 1 to 10
    print "Enter Customer # "; index
    input customer$
    if customer$ = "" then [quitEntry]   ' <- it isn't allowed to cut out of a for ... next loop like this
    cust$(index) = customer$
  next index
  [quitEntry]

   . . . is not allowed!  Rather use while ... wend:

  index = 1
  while customer$ <> "" and index <= 10
    print "Enter Customer # "; index
    input customer$
    cust$(index) = customer$
    index = index + 1
  wend



GET #handle, recordNumber

Description:

  GET is used after a random access file is opened to get a record of information
  (see FIELD) out of the file from a specified position.  For example:


  open "custdata.001" for random as #cust len = 70   ' open random access file
  field #cust, 20 as name$, 20 as street$, 15 as city$, 2 as state$, 10 as zip$, 3 as age

  ' get the data from record 1
  get #cust, 1

  print name$
  print street$
  print city$
  print state$
  print zip$
  print age

  close #cust
  end


Note:  See also PUT, FIELD



GETTRIM #handle, recordNumber

Description:

  The GETTRIM command is exactly like the GET command, but when data is
  retrieved, all leading and trailing blank space is removed from all data fields
  before being committed to variables.



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 or equal to 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)



LOG( n )

Description:

  This function returns the natural log of  n.

Usage:

  print log( 7 )              produces:  1.9459101
  
  
  
MENU #handle, title,   text, branchLabel,   text, branchLabel,  |  , . . .

Description:

  Adds a pull down menu to the window at #handle.  Title specifies the title of
  the menu, as seen on the menu bar of the window, and each  text,
  branchLabel  pair after the title adds a menu item to the menu, and tells
  Liberty BASIC where to branch to when the menu item is chosen.  The  |
  character can optionally be placed between menu items, to cause a seperating
  line to be added between the items with the menu is pulled down.

  As an example, if you wanted to have a graphics window opened, and then
  be able to pull down some menus to control color and geometric objects, your
  opening code might look like this:

  menu #geo, &Colors, &Red, [setRed], &Green, [setGreen], &Blue, [setBlue]
  menu #geo, &Shapes, &Rectangle, [asRect], &Triangle, [asCircle], &Line, [asLine]
  open "Geometric wite-board" for graphics_nsb as #geo
  input r$  ' stop and wait for a menu item to be chosen

  Notice that the MENU lines must go before the OPEN statement, and must
  use the same handle as the window that it will be associated with (#geo in this
  case).  This is the same with  the BUTTON statement (see BUTTON).  See
  that execution must be stopped at an input statement for the menu choice to
  be acted upon.  This is also the same as with BUTTON.

  Also notice that the & character placed in the title and text items for the menu
  determines the accelerator placement for each menu.  Try experimenting.




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




NOMAINWIN

Description:

  This command instructs Liberty BASIC not to open a main window for the
  program that includes this statement.  Some simple programs which do not use
  seperate windows for graphics, spreadsheet, or text may use only the main
  window.  Other programs may not need the main window to do their thing, and
  so simply including NOMAINWIN  somewhere in your program source
  will prevent the window from opening.

  If NOMAINWIN is used, when all other windows owned by that program
  are closed, then the program terminates execution automatically.

  For examples of the usage of NOMAINWIN, examine the included Liberty
  BASIC programs (buttons1.bas for example).



NOTICE "string expression"

Description:

  This command pops up a dialog box which displays "string expression" and
  which has a button OK which the user presses after the message is read. 
  Pressing Enter also closes the dialog box.

  Two forms are allowed.  If "string expression" has no Cr character (ASCII 13),
  then the title of the dialog box will be 'Notice' and "string expression" will be
  the message displayed inside the dialog box.  If "string expression" does have
  a Cr character, then the part of "string expression" before Cr will be used as
  the title for the dialog box, and the part of "string expression" after Cr will be
  displayed as the message inside.

Usage:

    notice "Super Stats is Copyright 1992, Mathware"


Or:

    notice "Fatal Error!" + chr$(13) + "The entry buffer is full!"
  


OPEN string FOR purpose AS #handle {LEN = #}

Description:

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

Using OPEN with 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

  LEN = # - this is an optional addition for use only when opening a random
                access file.  The # determines how many characters long each
                record in the file is.  If this is not specified, the default length is
                128 characters.  See FIELD, GET, and PUT.

Using OPEN with 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.
  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, or
  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 . . . "
  .
  .



PUT #handle, recordNumber

Description:

PUT is used after a random access file is opened to place a record of information
(see FIELD) into the file at a specified position.  For example:


  open "custdata.001" for random as #cust len = 70   ' open a random access file
  field #cust, 20 as name$, 20 as street$, 15 as city$, 2 as state$, 10 as zip$, 3 as age
  
  ' enter data into customer variables
  input name$
  .
  .

  ' put the data into record 1
  put #cust, 1

  close #cust
  end


Note:  See also GET, FIELD



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 or equal to
  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.  The code between WHILE and
  WEND will always execute at least once.  Once execution reaches the WEND
  statement, for as long as the WHILE expression evaluates to true, then execution
  will jump back to the WHILE statement.  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."
  token$ = "?"
  while token$ <> ""
      index = index + 1
      tokens$ = word$(sentence$, index)
      print token$
  wend

Produces:

  and
  many
  miles
  to
  go
  before
  I
  sleep.