basic-man.txt

比较早的一款BASIC解释器 可作为学习BASIC解释器的一个参考

        inkey$

                Return one character from the keyboard if input is
                available. Returns a zero length string { "" } if no
                keyboard input is available.  Non-blocking.  Can be
                used for keyboard polling.

        input$( EXPR { , FILENUM } )

                Returns EXPR characters from file FILENUM. If f is not
                present then get input from the console keyboard.

        mid$( a$, i { , j } )

                Returns a substring of a$ starting at the i'th
                positions and j characters in length. If the second
                parameter is not specified then the substring is
                taken from the start position to the end of a$.

        right$(a$, EXPR )

                Returns the right EXPR characters of a$.

        left$(a$, EXPR )

                Returns the left EXPR characters of a$.

        field$( STRINGVAL, VAL { , STRINGVAL } )

                Returns the N-th field of the first string.  If the
                optional string is present then use the first character
                of that string as the field separator.  The default
                separator is a space.  Similar to UNIX 'awk' fields.

                e.g.  field$("1 22 333 4", 3)  returns  "333"

                If VAL is -1 then returns a string with a length
                equal to the number of seperators in the first string.

        hex$( VAL { , EXPR } )
        bin$( VAL { , EXPR } )

                Returns the hexadecimal or binary string representation
                corresponding to VAL.  If EXPR is present then the
                string is padded with zeros to make it that length.

        lcase$( STRINGVAL )

                Returns STRINGVAL in all lower case characters.

        errorstatus$

                Returns the error message for the last error.


    OPERATORS

        The following math operators  are available:

                ^       exponentiation
                *       multiplication
                /       division
                mod     remainder
                +       addition
                -       subtraction

        logical operators: (any non-zero value is true)

                not     logical not

        bitwise operators:

                and     bitwise and
                or      bitwise or
                xor     bitwise exclusive-or

        comparison operators:

                <=      less than or equal
                <>      not equal to
                >=      greater than or equal
                =       equal
                >       greater than
                <       less than

        x$=y$, x$y$, x$<=y$, x$>=y$, x$<>y$

                String comparisons; result is 1 if true, 0 if false.

        Operator precedence (highest to lowest):

                ( )
                functions()
                ^
                -{unary_minus} 
                * / mod
                + -
                = < > <= >= <>
                not
                and
                or xor


    UNIX/linux commands:

        open "pipe:" + STRINGEXPR for input as # FNUM
                
                Opens an input pipe with STRINGEXPR as the input
                process command string.

                example: open "pipe:/bin/ls -l" for input as #1

        open "socket:" + STRINGEXPR , EXPR for input as # FNUM
        open "socket:" + STRINGEXPR , EXPR for output as # FNUM
                
                Open a socket to the server and port specified by
                STRINGEXPR and EXPR.  The input port must be opened
                before the output port.

        #cbas#run_only

                When used in a Basic program file, upon load sets
                the  Chipmunk  Basic  interpreter to run-only mode.
                Interactive mode disabled.  Thus the Stop and  End
                commands and the use of Ctrl-C will quit the
                interpreter.


    UNIX/linux functions:

        argv$
                Returns the UNIX shell command line arguments.

        sys( STRINGVAL )

                UNIX system call.  The string parameter is given to
                the shell as a command.  Returns exit status.

        getenv$( STRINGVAL )

                Returns value for environment name STRINGVAL.
    
        fn pid()
        fn ppid()
        fn uid()

                Returns system process and user info.

        fn sysfork()

                Forks process.  Returns 0 to the child process and
                the pid of new process to the parent process.

        fn kill( STRINGVAL )

                Deletes the file named by STRINGVAL.  Returns 0 if
                successful.

        exit( EXPR )

                Exits Basic interpreter with status value of EXPR.


    Macintosh commands:

        *** NOTE ***

                Many MacOS specific functions and commands are only
                documented in the Chipmunk Basic quick reference file.

        gotoxy VAL, VAL

                Set the horizontal and vertical location of the
                text output cursor.  (0,0) is the upper left corner.

        moveto VAL, VAL

                Sets the (x,y) location of the graphics pen.

        lineto VAL, VAL

                Draws a line from the current pen location to location
                (x,y) in the graphics window.

        window x, y, char_cols, char_lines

                Change the text console window position and size.

        morse STRINGVAL { , VAL, VAL, VAL, VAL }

                Plays morse code through the speaker.
                The parameters are: dot-speed-wpm, volume{0..100},
                word-speed-wpm, frequency{in Hz or cps}

        sound VAL, VAL, VAL 

                The parameters are:
                frequency{in Hz}, seconds_duration, volume{0..100}

        say STRINGVAL

                Speaks STRINGVAL if the Speech Manager Extension is
                resident.  Try "say a$,200,46,1" for faster speech.

        open "SFGetFile" for input  as #FNUM
        open "SFPutFile" for output as #FNUM

                Puts up a standard file dialog for the file name.

        files { STRINGVAL }

                Displays a listing of files in the named or current
                directory.

    Macintosh functions:

        fre
                Returns the amount of memory left for program use. 

        date$
                Returns a string corresponding to the current date.

        time$
                Returns a string corresponding to the current time.

        pos(VAL)

                Returns the horizontal position of the text cursor.
                If VAL is negative returns the vertical position.

        errorstatus$

                Also returns the full path name of the program and
                files opened by SFGetFile and SFPutFile (Only under
                System 7 and only if the path name fits in a string
                variable)


    Macintosh menu items:

        Open or O       will put up a dialog to allow selection
                        of a program file to load.  Basic Program
                        file names must end with a ".bas" suffix.

        Copy            will allow copying picts from the graphics
                        window.

        .               Command-period will stop program execution.


    RESERVED WORDS AND SYMBOLS

        + - * / ^ mod  and or xor not  > < >= <= <> = ()
        sqr log exp sin cos tan atn  pi
        abs sgn int rnd peek val asc len
        mid$ right$ left$ str$ chr$  lcase$ ucase$
        goto  if then else endif  gosub return
        for to step next  while wend  select case
        rem  let  dim erase  data read restore   field$
        input print open for output append as close# load save
        random lof loc get put   
        inkey$  input$ eof  files  fgetbyte# fseek# fputbyte
        run stop end exit quit cont  renum  new clear
        date$ time$ timer  sound morse say  doevents
        home cls gotoxy htab vtab pos 
        graphics sprite pset moveto lineto window scrn mouse
        varptr peek poke fre push pop  isarray
        sub call usr  def fn
        type class extends  string integer single double
        asin acos sinh cosh tanh log10 floor true false ubound

        eqv imp  static  option degrees radians redim
        msgbox  do loop until break
        method private public local   menu dialog memstat()
        draw play  bload bsave  min max mat
        each  resume  function
        key is each set width swap


    CONVENTIONS

        EXPR            an expression that evaluates to a numeric value.
        STRINGEXPR      a string expression.
        VAR             a numeric variable.
        STRINGVAR       a string variable. Name must end with a "$".
        INTEGERVAR      a 16-bit variable. Name must end with a "%".

        All program lines must begin with a line number.
        Using spaces (indentation) between the line number and
        program statements is legal.  Line numbers can be
        between 1 and 2147483647.  Programs lines must be no
        longer than 254 characters in length.

        Subroutine names starting with "fn" are reserved for the
        (obsolete) def fn functions.

        Hexadecimal numbers can be entered by preceding them with
        a "0x" as in 0x02ae, or by "&h" as in &h0172.

        Multiple statements may be given on one line, separated by
        colons:

                10 INPUT X : PRINT X : STOP


    DIAGNOSTICS

        Some errors can be caught by the user program using the
        "on error goto" command. If no error trapping routine has been
        supplied then program execution is terminated and a message is
        printed with the corresponding line number.


    CHANGES
    
        v3.6.1   - changed precedence of unary minus (-) to below
                     exponentiation (^) to match ANSI/ISO specification.
                 - changed default matrix origin to 1
                 - added mat print commmand.
        v3.6.0   - added unix exit status, fn kill(), fn bigendian()
        v3.5.9b4 - fixed def fn array parameters, added atn(x,y)
        v3.5.9b3 - fixed bugs with if():, instr(), mid$ & val("..")
        v3.5.9   - fixed bugs in format$() & intl. string comparisons
        v3.5.8b7 - fixed  bugs in array assignment, the read/data
                   statement, fputbyte(), and ELSEIF nesting
                 - added the MAT INVERT statement
        v3.5.8   - changed int() to round towards -infinity.
        v3.5.7b3 - added network socket i/o
        v3.5.7b2 - fixed unix/linux rnd() function
        v3.5.7b1 - fixed a problem with array indexes > 65k
        v3.5.3  - allow integer (i%) variables as for/next loop indices
        v3.4.7  - lower precedence of NOT operator
                - disabled ON GOTO range checking
        v3.4.6  - added MAT matrix statements
        v3.4.0  - OPEN ELSE added
        v3.3.4  - changed integer conversion to rounding
                - changed sub return values to: sub_name = x
                - added reserved words for: true false
        v3.3.3  - added acos, tanh, log10
        v3.2.8  - added class definitions
        
        Many others ...

    BUGS

        Many.  Perhaps competitive with Central American rain forests.

        FOR/NEXT loops with integer indices require a variable in the
        NEXT statement. Integer arrays can only have a dimension of
        one and will only work in assignment (LET) statements.  All
        arithmetic on integer variables is done using floating point
        arithmetic.  DIM AS DOUBLE and DIM AS INTEGER statements are
        ignored.

        Many string functions (except +, MID$, LEN and INSTR) silently
        truncate their results to 254 characters (e.g. without
        warning). All string function may silently truncate strings
        longer than 32766 characters. Any operation on strings longer
        than 254 characters will cause the program to run slower.

        Comments starting with ' sometimes can't be used after
        statements that can end with a string parameter. ( : '
        should always work.)

        Any variables used as a CLASS, or TYPE, globally overide all
        local variables of the same names.  Local TYPE'd variables
        must be declared globally as TYPE'd variables.  Named SUBroutines
        are slower than GOSUBs. The combined length of a SUBroutine name
        and any local variables declared STATIC must be less than 29
        characters.

        Can't CONTinue from an error inside a named SUB subroutine.

        The PRINT USING format string doesn't recognize comma's,
        underscores and many other common format characters.

        Macintosh screen editing will only recognise the last line
        modified before a RETURN or ENTER key.  The EDIT command and
        Mac screen editing are incompatible.

        There are many undocumented graphics and sprite commands
        and keywords in the Macintosh port.  See the accompanying
        README and Chipmunk Basic quick-reference file.


    DISCLAIMER

        There is no warranty that this document is accurate.

    SEE ALSO

        The Chipmunk Basic Home Page:

                http://www.nicholson.com/rhn/basic

    
    AUTHORS

        David Gillespie wrote basic.p 1.0 and the p2c lib.
        Ron Nicholson (rhn AT nicholson.com) added file i/o, graphics
        and did the Unix, Macintosh and PowerMac port. (1990-1997Nov)

    Portions of this document are Copyright (C) 1989 Dave Gillespie.
    Copyright (C) 1994,1998,2004 Ronald H. Nicholson, Jr.
    All rights reserved.  
    "Applesoft" is a trademark of Apple Computer, Inc., etc.