yabasic.1

Linux下VB解释器

   execute()
          execute a user defined subroutine, which must return a number

   exit
          terminate your program

   pause
          pause, sleep, wait for the specified number of seconds

   peek
          retrieve various internal informations

   peek$
          retrieve various internal string-informations

   poke
          change selected internals of yabasic

   rem
          start a comment

   sleep
          pause, sleep, wait for the specified number of seconds

   system$()
          hand a statement over to your operating system and return its output

   system()
          hand a statement over to your operating system and return its
          exitcode

   time$
          return a string containing the current time

   to
          this keyword appears as part of other statements

   wait
          pause, sleep, wait for the specified number of seconds

   //
          starts a comment

   :
          separate commands from each other

Graphics and printing

   backcolor
          specify the colour for subsequent drawing of the background

   box
          draw a rectangle. A synonym for rectangle

   circle
          draws a circle in the graphic-window

   clear
          Erase circles, rectangles or triangless

   clear window
          clear the graphic window and begin a new page, if printing is under
          way

   close curve
          close a curve, that has been drawn by the line-command

   close window
          close the graphics-window

   colour
          specify the colour for subsequent drawing

   dot
          draw a dot in the graphic-window

   fill
          draw a filled circles, rectangles or triangles

   getbit$()
          return a string representing the bit pattern of a rectangle within
          the graphic window

   line
          draw a line

   mouseb
          extract the state of the mousebuttons from a string returned by
          inkey$

   mousemod
          return the state of the modifier keys during a mouseclick

   mousex
          return the x-position of a mouseclick

   mousey
          return the y-position of a mouseclick

   new curve
          start a new curve, that will be drawn with the line-command

   open window
          open a graphic window

   putbit
          draw a rectangle of pixels into the graphic window

   rectangle
          draw a rectangle

   triangle
          draw a triangle

   text
          write text into your graphic-window

   window origin
          move the origin of a window

Chapter 6. All commands and functions of yabasic grouped alphabetically

   A
   B
   C
   D
   E
   F
   G
   H
   I
   L
   M
   N
   O
   P
   R
   S
   T
   U
   V
   W
   X
   Special characters
   Reserved Words

A

   abs() - returns the absolute value of its numeric argument
   acos() - returns the arcus cosine of its numeric argument
   and - logical and, used in conditions
   and() - the bitwise arithmetic and
   arraydim() - returns the dimension of the array, which is passed as an array
          reference

   arraysize() - returns the size of a dimension of an array
   asc() - accepts a string and returns the position of its first character
          within the ascii charset

   asin() - returns the arcus sine of its numeric argument
   at() - can be used in the print-command to place the output at a specified
          position

   atan() - returns the arctangent of its numeric argument

Name

   abs() - returns the absolute value of its numeric argument

Synopsis

y=abs(x)

Description

   If the argument of the abs-function is positive (e.g. 2) it is returned
   unchanged, if the argument is negative (e.g. -1) it is returned as a
   positive value (e.g. 1).

Example

print abs(-2),abs(2)
          

   This example will print 2 2

See also

   sig
     _________________________________________________________________

Name

   acos() - returns the arcus cosine of its numeric argument

Synopsis

x=acos(angle)

Description

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

Example

print acos(0.5),acos(cos(pi))
          

   This example will print 1.0472 3.14159 which are pi/3 and pi respectively.

See also

   cos, asin
     _________________________________________________________________

Name

   and - logical and, used in conditions

Synopsis

if (a and b) ...
while (a and b) ...

Description

   Used in conditions (e.g within if, while or until) to join two expressions.
   Returns true, if and only if its left and right argument are both true and
   false otherwise.

   Note, that logical shortcuts may take place.

Example

input "Please enter a number" a
if (a>=1 and a<=9) print "your input is between 1 and 9"
          

See also

   or,not
     _________________________________________________________________

Name

   and() - the bitwise arithmetic and

Synopsis

x=and(a,b)

Description

   Used to compute the bitwise and of both its argument. Both arguments are
   treated as binary numbers (i.e. a series of 0 and 1); a bit of the resulting
   value will then be 1, if both arguments have a 1 at this position in their
   binary representation.

   Note, that both arguments are silently converted to integer values and that
   negative numbers have their own binary representation and may lead to
   unexpected results when passed to and.

Example

print and(6,3)
          

   This will print 2. This result is clear, if you note, that the binary
   representation of 6 and 3 are 110 and 011 respectively; this will yield 010
   in binary representation or 2 as decimal.

See also

   or, eor and not
     _________________________________________________________________

Name

   arraydim() - returns the dimension of the array, which is passed as an array
   reference

Synopsis

a=arraydim(b())

Description

   If you apply the arraydim()-function on a one-dimensional array (i.e. a
   vector) it will return 1, on a two-dimensional array (i.e. a matrix) it will
   return 2, and so on.

   This is mostly used within subroutines, which expect an array among their
   parameters. Such subroutines tend to use the arraydim-function to check, if
   the array which has been passed, has the right dimension. E.g. a subroutine
   to multiply two matrices may want to check, if it really is invoked with two
   2-dimensional arrays.

Example

dim a(10,10),b(10)
print arraydim(a()),arraydim(b())
          

   This will print 2 1, which are the dimension of the arrays a() and b(). You
   may check out the function arraysize for a full-fledged example.

See also

   arraysize and dim.
     _________________________________________________________________

Name

   arraysize() - returns the size of a dimension of an array

Synopsis

x=arraysize(a(),b)

Description

   The arraysize-function computes the size of a specified dimension of a
   specified array. Here, size stands for the maximum number, that may be used
   as an index for this array. The first argument to this function must be an
   reference to an array, the second one specifies, which of the multiple
   dimensions of the array should be taken to calculate the size.

   An Example involving subroutines: Let's say, an array has been declared as
   dim a(10,20) (that is a two-dimensional array or a matrix). If this array is
   passed as an array reference to a subroutine, this sub will not know, what
   sort of array has been passed. With the arraydim-function the sub will be
   able to find the dimension of the array, with the arraysize-function it will
   be able to find out the size of this array in its two dimensions, which will
   be 10 and 20 respectively.

   Our sample array is two dimensional; if you envision it as a matrix this
   matrix has 10 lines and 20 columns (see the dim-statement above. To state it
   more formally: The first dimension (lines) has a size of 10, the second
   dimension (columns) has a size of 20; these numbers are those returned by
   arraysize(a(),1) and arraysize(a(),2) respectively. Refer to the example
   below for a typical usage.

Example


rem
rem  This program adds two matrices elementwise.
rem

dim a(10,20),b(10,20),c(10,20)

rem  initialization of the arrays a() and b() 
for y=1 to 10:for x=1 to 20
   a(y,x)=int(ran(4)):b(y,x)=int(ran(4))
next x:next y

matadd(a(),b(),c())

print "Result:"
for x=1 to 20
   for y=10 to 1 step -1
      print c(y,x)," ";
   next y
   print
next x

sub matadd(m1(),m2(),r())

   rem  This sub will add the matrices m1() and m2()
   rem  elementwise and store the result within r()
   rem  This is not very useful but easy to implement.
   rem  However, this sub excels in checking its arguments
   rem  with arraydim() and arraysize()

   local x:local y
   
   if (arraydim(m1())<>2 or arraydim(m2())<>2 or arraydim(r())<>2) then
      error "Need two dimensional arrays as input"
   endif

   y=arraysize(m1(),1):x=arraysize(m1(),2)
   if (arraysize(m2(),1)<>y or arraysize(m2(),2)<>x) then
      error "The two matrices cannot be added elementwise"
   endif

   if (arraysize(r(),1)<>y or arraysize(r(),2)<>x) then
      error "The result cannot be stored in the third argument"
   endif

   local xx:local yy
   for xx=1 to x
      for yy=1 to y
         r(yy,xx)=m1(yy,xx)+m2(yy,xx)
      next yy
   next xx

 end sub

          

See also

   arraydim and dim.
     _________________________________________________________________

Name

   asc() - accepts a string and returns the position of its first character
   within the ascii charset

Synopsis

a=asc(char$)

Description

   The asc-function accepts a string, takes its first character and looks it up
   within the ascii-charset; this position will be returned. The asc-function
   is the opposite of the chr$-function. There are valid uses for asc, however,
   comparing strings (i.e. to bring them into alphabetical sequence) is not
   among them; in such many cases you might consider to compare strings
   directly with <, = and > (rather than converting a string to a number and
   comparing this number).

Example

input "Please enter a letter between 'a' and 'y': " a$
if (a$<"a" or a$>"y") print a$," is not in the proper range":end
print "The letter after ",a$," is ",chr$(asc(a$)+1)
          

See also

   chr$
     _________________________________________________________________

Name

   asin() - returns the arcus sine of its numeric argument

Synopsis

angle=asin(x)

Description

   acos is the arcus sine-function, i.e. the inverse of the sin-function. Or,
   more elaborate: It Returns the angle (in radian, not degree !), which, fed
   to the sine-function will produce the argument passed to the asin-function.

Example

print asin(0.5),asin(sin(pi))
          

   This will print 0.523599 -2.06823e-13 which is pi and almost 0 respectively.

See also

   sin, acos
     _________________________________________________________________

Name

   at() - can be used in the print-command to place the output at a specified
   position

Synopsis

clear screen
...
print at(a,b)
print @(a,b)

Description