yabasic.1

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   The at-clause takes two numeric arguments (e.g. at(2,3)) and can be inserted
   after the print-keyword. at() can be used only if clear screen has been
   executed at least once within the program (otherwise you will get an error).

   The two numeric arguments of the at-function may range from 0 to the width
   of your terminal minus 1, and from 0 to the height of your terminal minus 1;
   if any argument exceeds these values, it will be truncated accordingly.
   However, yabasic has no influence on the size of your terminal (80x25 is a
   common, but not mandatory), the size of your terminal and the maximum values
   acceptable within the at-clause may vary. To get the size of your terminal
   you may use the peek-function: peek("screenwidth") returns the width of your
   terminal and peek("screenheight") its height.

Example

clear screen
maxx=peek("screenwidth")-1:maxy=peek("screenheight")-1
for x=0 to maxx
  print at(x,maxy*(0.5+sin(2*pi*x/maxx)/2)) "*"
next x
          

   This example plots a full period of the sine-function across the screen.

See also

   print, clear screen, color
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Name

   atan() - returns the arctangent of its numeric argument

Synopsis

angle=atan(a,b)
angle=atan(a)

Description

   atan is the arctangent-function, i.e. the inverse of the tan-function. Or,
   more elaborate: It Returns the angle (in radian, not degree !), which, fed
   to the tan-function will produce the argument passed to the atan-function.

   The atan-function has a second form, which accepts two arguments: atan(a,b)
   which is (mostly) equivalent to atan(a/b) except for the fact, that the
   two-argument-form returns an angle in the range -pi to pi, whereas the
   one-argument-form returns an angle in the range -pi/2 to pi/2. To understand
   this you have to be good at math.

Example

print atan(1),atan(tan(pi)),atan(-0,-1),atan(-0,1)
          

   This will print 0.463648 2.06823e-13 -3.14159 3.14159 which is pi/4, almost
   0, -pi and pi respectively.

See also

   tan, sin

B

   backcolor - change color for background of graphic window
   backcolour - see backcolor
   beep - ring the bell within your computer; a synonym for bell
   bell - ring the bell within your computer (just as beep)
   bin$() - converts a number into a sequence of binary digits
   bind() - Binds a yabasic-program and the yabasic-interpreter together into a
          standalone program.

   box - draw a rectangle. A synonym for rectangle
   break - breaks out of a switch statement or a loop

Name

   color - change color for background of graphic window

Synopsis

backcolour red,green,blue
backcolour "red,green,blue"

Description

   Change the color, that becomes visible, if any portion of the window is
   erased, e.g. after clear window or clear line. Note however, that parts of
   the window, that display the old background color will not change.

   As with the color-command, the new background color can either be specified
   as a triple of three numbers or as a single string, that contains those
   three numbers sperated by commas.

Example

open window 255,255
for x=10 to 235 step 10:for y=10 to 235 step 10
        backcolour x,y,0
        clear window
        sleep 1
next y:next x
          

   This changes the background colour of the graphic window repeatedly and
   clears it every time, so that it is filled with the new background colour.

See also

   open window, color, line, rectangle, triangle, circle
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Name

   backcolour - see backcolor

Synopsis

backcolour red,green,blue
backcolour "red,green,blue"

See also

   color
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Name

   beep - ring the bell within your computer; a synonym for bell

Synopsis

beep

Description

   The bell-command rings the bell within your computer once. This command is
   not a sound-interface, so you can neither vary the length or the height of
   the sound (technically, it just prints \\a). bell is exactly the same as
   beep.

Example

beep:print "This is a problem ..."
          

See also

   beep
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Name

   bell - ring the bell within your computer (just as beep)

Synopsis

bell

Description

   The beep-command rings the bell within your computer once. beep is a synonym
   for bell.

Example

print "This is a problem ...":beep
          

See also

   bell
     _________________________________________________________________

Name

   bin$() - converts a number into a sequence of binary digits

Synopsis

hexadecimal$=bin$(decimal)

Description

   The bin$-function takes a single numeric argument an converts it into a
   string of binary digits (i.e. zeroes and ones). If you pass a negative
   number to bin$, the resulting string will be preceded by a '-'.

   If you want to convert the other way around (i.e. from binary to decimal)
   you may use the dec-function.

Example

for a=1 to 100
  print bin$(a)
next a
          

   This example prints the binary representation of all digits between 1 and
   100.

See also

   hex$, dec
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Name

   bind() - Binds a yabasic-program and the yabasic-interpreter together into a
   standalone program.

Synopsis

bind("foo.exe")

Description

   The bind-command combines your own yabasic-program (plus all the libraries
   it does import) and the interpreter by copying them into a new file, whose
   name is passed as an argument. This new program may then be executed on any
   computer, even if it does not have yabasic installed.

   Please see the section about creating a standalone-program for details.

Example

if (!peek("isbound")) then
  bind "foo"
  print "Successfully created the standalone executable 'foo' !"
  exit
endif

print "Hello World !"
          

   This example creates a standalone program foo from itself.

See also

   The section about creating a standalone-program, the peek-function and the
   commandline options for Unix and Windows.
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Name

   box - draw a rectangle. A synonym for rectangle

Synopsis

See the rectangle-command.

Description

   The box-command does exactly the same as the rectangle-command; it is just a
   synonym. Therefore you should refer to the entry for the rectangle-command
   for further information.
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Name

   break - breaks out of a switch statement or a loop

Synopsis

break

Description

   break transfers control immediately outside the enclosing loop or switch
   statement. This is the preferred way of leaving a such a statement (rather
   than goto, which is still possible in most cases).

Example

for a=1 to 10
  break
  print "Hi"
next a

while(1)
  break
  print "Hi"
wend

repeat
  break
  print "Hi"
until(0)

switch 1
case 1:break
case 2:case 3:print "Hi"
end switch
          

   This example prints nothing at all, because each of the loops (and the
   switch-statement) does an immediate break (before it could print any "Hi").

See also

   for, while, repeat and switch.

C

   case - mark the different cases within a switch-statement
   chr$() - accepts a number and returns the character at this position within
          the ascii charset

   circle - draws a circle in the graphic-window
   clear - Erase circles, rectangles or triangles
   clear screen - erases the text window
   clear window - clear the graphic window and begin a new page, if printing is
          under way

   close - close a file, which has been opened before
   close curve - close a curve, that has been drawn by the line-command
   close printer - stops printing of graphics
   close window - close the graphics-window
   color - change color for any subsequent drawing-command
   colour - see color
   compile - compile a string with yabasic-code on the fly
   continue - start the next iteration of a for-, do-, repeat- or while-loop
   cos() - return the cosine of its single argument

Name

   case - mark the different cases within a switch-statement

Synopsis

switch a
  case 1
  case 2
  ...
end switch

...

switch a$
  case "a"
  case "b"
  ...
end switch

Description

   Please see the switch-statement.

Example

input a
switch(a)
  case 1:print "one":break
  case 2:print "two":break
  default:print "more"
end switch
          

   Depending on your input (a number is expected) this code will print one or
   two or otherwise more.

See also

   switch
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Name

   chr$() - accepts a number and returns the character at this position within
   the ascii charset

Synopsis

character$=chr$(ascii)

Description

   The chr$-function is the opposite of the asc-function. It looks up and
   returns the character at the given position within the ascii-charset. It's
   typical use is to construct nonprintable characters which do not occur on
   your keyboard.

   Nevertheless you won't use chr$ as often as you might think, because the
   most important nonprintable characters can be constructed using
   escape-sequences using the \\-character (e.g. you might use \\n instead of
   chr$(10) wherever you want to use the newline-character).

Example

print "a",chr$(10),"b"
          

   This will print the letters 'a' and 'b' in different lines because of the
   intervening newline-character, which is returned by chr$(10).

See also

   asc
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Name

   circle - draws a circle in the graphic-window

Synopsis

circle x,y,r
clear circle x,y,r
fill circle x,y,r
clear fill circle x,y,r

Description

   The circle-command accepts three parameters: The x- and y-coordinates of the
   center and the radius of the circle.

   Some more observations related with the circle-command:
     * The graphic-window must have been opened already.
     * The circle may well extend over the boundaries of the window.
     * If you have issued open printer before, the circle will finally appear
       in the printed hard copy of the window.
     * fill circle will draw a filled (with black ink) circle.
     * clear circle will erase (or clear) the outline of the circle.
     * clear fill circle or fill clear circle will erase the full area of the
       circle.

Example

open window 200,200

for n=1 to 2000
  x=ran(200)
  y=ran(200)
  fill circle x,y,10
  clear fill circle x,y,8
next n
          

   This code will open a window and draw 2000 overlapping circles within. Each
   circle is drawn in two steps: First it is filled with black ink (fill circle
   x,y,10), then most of this circle is erased again (clear fill circle x,y,8).
   As a result each circle is drawn with an opaque white interior and a 2-pixel
   outline (2-pixel, because the radii differ by two).

See also

   open window, open printer, line, rectangle, triangle
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Name

   clear - Erase circles, rectangles or triangles

Synopsis

clear rectangle 10,10,90,90
clear fill circle 50,50,20
clear triangle 10,10,20,20,50,30

Description

   May be used within the circle, rectangle or triangle command and causes
   these shapes to be erased (i.e. be drawn in the colour of the background).

   fill can be used in conjunction with and wherever the fill-clause may
   appear. Used alone, clear will erase the outline (not the interior) of the
   shape (circle, rectangle or triangle); together with fill the whole shape
   (including its interior) is erased.

Example

open window 200,200
fill circle 100,100,50
clear fill rectangle 10,10,90,90
          

   This opens a window and draws a pacman-like figure.

See also