TIMER
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QB64 only
QB64 Timing Alternatives
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A TIMER statement enables, turns off or stops timer event trapping. QBasic only uses the base timer, but QB64 can run many.
Syntax
- QuickBASIC
- TIMER {ON|STOP|OFF}
- QB64
- 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.
- 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(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!
- 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.
Examples
Example: How to update the time while printing at the same time in a program.
TIMER ON ' enable timer event trapping LOCATE 4, 2 ' set the starting PRINT position ON TIMER(10) GOSUB Clock ' set procedure execution repeat time DO WHILE INKEY$ = "": PRINT "A"; : SLEEP 6: LOOP TIMER OFF SYSTEM Clock: row = CSRLIN ' Save current print cursor row. col = POS(0) ' Save current print cursor column. LOCATE 2, 37: PRINT TIME$; ' print current time at top of screen. LOCATE row, col ' return to last print cursor position RETURN |
- NOTE: SLEEP will be interrupted in QBasic.
See also