📚 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