📚 DIM Syntax Diagram

This is a complex diagram.  To condense it a little bit, some details have been moved into smaller detail diagrams further below.

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📚 CIRCLE Syntax Diagram

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📚 SUB definition syntax diagrams

A subroutine (of the "structured BASIC" kind) is defined with a "SUB definition block", as per the following syntax diagram:

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(/EOL/ means "end of line.")

Details below for "SUB statement", "statement", and "statement exclusion list".

SUB statement syntax diagram:

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"Legal" statements that can be used in a SUB definition block can be any statement found in this list of BASIC statements with the exception of the following statements (illegal in SUB definition blocks):

• DECLARE FUNCTION
• DECLARE SUB
• DEFDV
• DEFINT
• DEFLNG
• DEFSNG
• DEFSTR
• END FUNCTION
• END RECORD
• END STRUCT
• END STRUCTURE
• END SUB
• END TYPE
• FUNCTION
• RECORD
• STRUCT
• STRUCTURE
• SUB
• TYPE

📚 Syntax diagram: BASIC Program Line Format

Second version (July 18):

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First version (July 17):

Click on the image to view full size

📚 CIRCLE Study: The "aspect" argument

The aspect argument will cause the CIRCLE statement to generate an oval ellipse instead of a circle, in either a horizontal or vertical orientation. (I should not be writing past my bedtime.  Thanks to Richard Russell for pointing out that the word should be "ellipse" and not "oval".)

Run the following program and take a look at the source code to see how the aspect argument works:

• Run the program
• View the source code

Click here for info about the CIRCLE statement.

🪲 Fixed: ByVal and ByRef keywords not working beyond the first argument

The recently added ByVal and ByRef keywords were only working of the first argument of a function/subroutine.

This new version of BAM now allows ByVal and ByRef on arguments beyond the first one.

📚 A Summary of Conditionals in BAM

Page Contents:

• Conditional Single-Line Structures
• Conditional Block Structures
• Conditional Functions
• References

Conditional Single-Line Structures

• IF...THEN LineIdentifier 

Example: 

25 PRINT "howdy";

SLEEP 0.5

IF TRUE THEN 25

• IF...GOTO LineIdentifier

Example: 

25 PRINT "howdy";

SLEEP 0.5

IF TRUE GOTO 25

• IF...THEN SingleStatement

Example: 

IF TRUE THEN PRINT "Howdy"

• IF...THEN MultiStatement

Example: 

IF TRUE THEN PRINT "Howdy"; : PRINT " There"

• IF...THEN...ELSE SingleStatements

Example: 

IF TRUE THEN PRINT "Yup" ELSE PRINT "Nope"

• ON GOTO

Example:

1 v% = VAL( RIGHT$( STR$( INT( TIMER * 10 ) ), 1) ) + 1

2 ON v% GOTO 10,11,12

3 GOTO 1

10 COLOR 15 : PRINT "0 "; : GOTO 20

11 COLOR 14 : PRINT "1 "; : GOTO 20

12 COLOR 13 : PRINT "2 "; : GOTO 20

20 SLEEP 0.001 : GOTO 1

• ON GOSUB

• ON RESTORE

• GOTO "EVAL" Clause

Example:

FUNCTION WhereToGo%(v%)

  SELECT CASE v%

    CASE 2    : WhereToGo% = 140

    CASE 5    : WhereToGo% = 190

    CASE 9    : WhereToGo% = 250

    CASE ELSE : WhereToGo% = 300

  END SELECT

END FUNCTION

  1 v% = VAL( RIGHT$( STR$( INT( TIMER * 10 ) ), 1) )

    GOTO EVAL( WhereToGo%(v%) )

140 COLOR 15 : PRINT "2 "; : GOTO 300

190 COLOR 14 : PRINT "5 "; : GOTO 300

250 COLOR 13 : PRINT "9 "; : GOTO 300

300 SLEEP 0.001 : GOTO 1

• GOSUB "EVAL" Clause

• RESTORE "EVAL" Clause

Conditional Block Structure

• IF...THEN Block

Example:

1 v% = VAL( RIGHT$( STR$( INT( TIMER * 10 ) ), 1) )

  IF     v% = 0 THEN : COLOR 15 : PRINT "0 ";

  ELSEIF v% = 1 THEN : COLOR 14 : PRINT "1 ";

  ELSEIF v% = 2 THEN : COLOR 13 : PRINT "2 ";

  ELSE               : COLOR 12 : PRINT "? ";

  END IF

  SLEEP 0.21

  GOTO 1

• SELECT CASE Block

Example: 

1 v% = VAL( RIGHT$( STR$( INT( TIMER * 10 ) ), 1) )

  SELECT CASE v%

    CASE    0 : COLOR 15 : PRINT "0 ";

    CASE    1 : COLOR 14 : PRINT "1 ";

    CASE    2 : COLOR 13 : PRINT "2 ";

    CASE ELSE : COLOR 12 : PRINT "? ";

  END SELECT

  SLEEP 0.21

  GOTO 1

• WHILE...WEND

Example: 

WHILE i% < 25
  i% = i% + 1
  PRINT i%
  SLEEP 0.1
WEND
END

Alternative Keyword Delimiters: 

• DO WHILE...WEND
• WHILE...LOOP
• DO WHILE...LOOP

• DO...LOOP

Example: 

DO
  i% = i% + 1
  PRINT i%
  SLEEP 0.1
  IF i% = 25 THEN END
LOOP

• DO...LOOP WHILE

Example: 

DO
  i% = i% + 1
  PRINT i%
  SLEEP 0.1
LOOP WHILE i% < 25
END

• DO...LOOP UNTIL

Example: 

DO
  i% = i% + 1
  PRINT i%
  SLEEP 0.1
LOOP UNTIL i% = 25
END

Conditional Functions

• IFF

Example:

PRINT IFF( TRUE, "Yup", "Nope")

• CHOOSE

Example:

1 v% = VAL( RIGHT$( STR$( INT( TIMER * 10 ) ), 1) ) + 1

  PRINT CHOOSE( v%, "Zero ", "One  ", "Two  " );

  SLEEP 0.21 : GOTO 1

• NVL$

Example:

1 v% = VAL( RIGHT$( STR$( INT( TIMER * 10 ) ), 1) ) + 1

  PRINT NVL$( CHOOSE( v%,"Zero ","One  ","Two  " ), "???  " );

  SLEEP 0.21 : GOTO 1

• MAX

Example:

a% = 5 : b% = 10

PRINT MAX( a%, b% )

• MIN

Example:

a% = 5 : b% = 10

PRINT MIN( a%, b% )

 

References:

• The Conditional (computer programming) article on Wikipedia
• Discussion in this post at the "BASIC Programming Language" Facebook group