Q(uick)BASIC Function: PLAY

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PLAY

An event-trapping function that returns the number of notes currently in the background-music queue

Worth knowing

Useful and cross-version information about the programming environments of QBasic and QuickBasic.

Syntax

PLAY(n)

Description/Parameter(s)

n	Any numeric expression.

Example

Music$ = "MBT180o2P2P8L8GGGL2E-P24P8L8FFFL2D"
PLAY Music$
WHILE PLAY(0) > 5: WEND
PRINT "Just about done!"

Syntax

PLAY(n)

Description/Parameter(s)

The argument n is a dummy argument and may be any numeric value.

PLAY(n) will return 0 when the user is in music-foreground mode.

Syntax

PLAY (n)

Description/Parameter(s)

n	A dummy argument that may be any numeric value. It is not used by the PLAY function.
The PLAY function is not available for OS/2 protected mode.

Example

This example uses the PLAY statements and the PLAY and VARPTR$ functions to play continuous music by calling an event-handling subroutine when the background music buffer goes from three to two notes.

CLS
'Call subroutine Replay when the music buffer goes from 3 to 2 notes.
ON PLAY(3) GOSUB Replay
'Turn on event trapping for PLAY.
PLAY ON
'Define a string containing the melody.
FElise$ = "o3 L8 E D+ E D+ E o2 B o3 D C L2 o2 A"
PLAY "MB X" + VARPTR$(FElise$)
'Suspend event trapping until next PLAY ON but remember events that occur
'while event trapping is disabled.
PLAY STOP
'Introduce a variable-length delay.
LOCATE 23, 1: PRINT "Press any key to continue."
DO
LOOP WHILE INKEY$ = ""
 
'Re-enable play event trapping remembering that a PLAY event has occurred.
PLAY ON
LOCATE 23, 1: PRINT "Press any key to stop.    "
'Loop until a key is pressed.
DO
    GOSUB BackGround
LOOP WHILE INKEY$ = ""
'Disable PLAY event processing.
PLAY OFF
'Count down to 0 notes in the queue.
DO
    GOSUB BackGround
LOOP UNTIL NoteCount = 0
END
 
'PLAY event-handling subroutine.
Replay:
    'Increment and print a counter each time.
    Count% = Count% + 1
    LOCATE 3, 1: PRINT "Replay routine called"; Count%; "time(s)";
    'PLAY it again to fill the buffer.
    PLAY "MB X" + VARPTR$(FElise$)
RETURN
 
'Background music queue reporting subroutine.
BackGround:
    'Get a notecount.
    NoteCount = PLAY(0)
    LOCATE 1, 1
    PRINT "Background queue notes remaining --> "; NoteCount
    'Loop until Notecount changes or equals 0.
    DO
    LOOP UNTIL NoteCount <> PLAY(0) OR NoteCount = 0
RETURN