
       ͻ
         Lesson 7 Part 020 F-PC 3.5 Tutorial by Jack Brown 
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Lesson 6 Review ( continued )

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               Number Formatting Operators.   
             

PAD  ( -- addr )  Leave address of output buffer.

The variable HLD points to the current position in the output buffer.
HLD is initialized to PAD by  <# below and is decremented by 1 just
before another ASCII digit is added to the output.

VARIABLE  HLD    Pointer to current output address in below PAD .

HOLD   ( n -- )  Add ASCII character n to string being formed
                 and decrement HLD


<#     ( -- )    Start numeric conversion, initialize HLD for
                 new output.


#>   ( dn -- addr len )  Terminate numeric conversion.


SIGN ( n -- )  If n is negative insert a -ve sign in the output string.


#  ( dn -- dn' ) Convert a single digit using the current number BASE.

#S  ( dn -- dn') Convert all remaining digits.

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                    Compiler Extension   
                 

IMMEDIATE   is used right after the definition of a word to declare it
            to be IMMEDIATE. An IMMEDIATE word will execute at compile
            time instead of being compiled.

LITERAL     compiles the stack number in to the dictionary.
            LITERAL  is an IMMEDIATE word itself.

' ( tick )  Get the cfa of the next word in the input stream.
            '  is not IMMEDIATE in F-PC ( it was in Fig Forth).

STATE       a system variable that is true if the system is
            in compile mode and false if the system is in
            interpretive mode.

[COMPILE]   force the compilation of an IMMEDIATE word when it
            would other wise execute.

COMPILE     When the word containing  COMPILE <xxx>  executes
            the word <xxx> will be compile into the dictionary.

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                   The Case Statement   
                

CASE ... OF ... ENDOF ...  ENDCASE

CASE    causes an index value to be compared to a series of values.

OF      is equivalent to  OVER = IF DROP
ENDOF   is equivalent to  ELSE
        Any number of OF .. ENDOF  pairs may be used.

ENDCASE is equivalent of the appropriate number of THENs

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   Please Move to Lesson 7 Part 030 

