QB64-PE/internal/help/TIMER_(statement).txt

A '''TIMER''' statement enables, turns off or stops timer event trapping. Qbasic only uses the base timer, but '''QB64''' can run many.


QB {{PageSyntax}} 

:::TIMER {ON|STOP|OFF}

QB64 {{PageSyntax}} 

:::TIMER(''number%'') {ON|STOP|OFF|FREE}


{{Parameters}}
* ''number'' denotes a specific numbered timer event in '''QB64 only'''. QB64 can run many timer events at once including the base timer.
* TIMER ON enables event trapping of an [[ON TIMER (n)]] statement. While enabled, a check is made after every code statement to see if the specified time has elapsed and the ON TIMER [[GOSUB]] (or [[SUB]] in QB64) procedure is executed.
* TIMER STOP disables timer event trapping. When an event occurs while stopped, it is remembered. If timer events are turned back on later, any remembered events are immediately executed. 
* TIMER OFF turns timer event trapping completely off and no subsequent events are remembered.

<center>'''QB64 only'''</center>
* Get a TIMER number from [[_FREETIMER]] ONLY except when the base timer(no number or 0) is used. Use specific variables or an array to hold each event number value for later reference.
* If the TIMER number is omitted or 0, the TIMER used is the base timer.
* Specific TIMER events can be enabled, suspended, turned off or freed using [[TIMER (statement)|TIMER(n)]] ON, STOP, OFF or FREE.
* TIMER(n) '''FREE''' clears a specific timer event when it is no longer needed. '''The base TIMER or TIMER(0) cannot be freed!''' 


<center>'''QB64 Timing Alternatives'''</center>
* The [[TIMER]] function can be used to find timed intervals down to 1 millisecond(.001) accuracy.
* The [[_DELAY]] statement can be used to delay program execution for intervals down to milliseconds.
* [[_LIMIT]] can slow down loops to a specified number of frames per second. This can also alleviate a program's CPU usage.


''Example:'' How to update the time while [[PRINT|printing]] at the same time in a program.
{{CodeStart}} '' ''
  TIMER ON ' enable timer event trapping
  LOCATE 4, 2 ' set the starting PRINT position
  {{Cl|ON TIMER(n)|ON TIMER}}(10) GOSUB Clock ' set procedure execution repeat time
  DO WHILE INKEY$ = "": PRINT "A"; : SLEEP 6: LOOP
  TIMER OFF
  {{Cl|SYSTEM}}

 Clock:
  row = {{Cl|CSRLIN}} ' Save current print cursor row.
  col = {{Cl|POS|POS(0)}} ' Save current print cursor column.
  LOCATE 2, 37: PRINT {{Cl|TIME$}}; ' print current time at top of screen.
  LOCATE row, col ' return to last print cursor position 
 {{Cl|RETURN}} '' ''
{{CodeEnd}}
: NOTE: SLEEP will be interrupted in Qbasic.


''See also:'' 

* [[ON TIMER(n)]], [[TIMER]](function)

* [[_DELAY]], [[_LIMIT]]



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