SLEEP


Waits until a specified time has elapsed, or a key is pressed.

Syntax:
declare sub Sleep ( byval amount as long = -1 )
declare function Sleep ( byval amount as long , byval keyflag as long ) as long

Usage:
Sleep [ amount [, keyflag ]]
result = Sleep ( amount, keyflag )

Parameters:
amount
Optional number of milliseconds to wait (default is to wait for a key press).
keyflag
Optional flag; give it a value of 0 for a normal sleep, or 1 to specify that the wait cannot be interrupted by a key press.

Return Value:
Returns 1 if keyflag was not a valid value (i.e. something other than 0 or 1) to indicate failure, or 0 otherwise.

Description:
Sleep will wait until amount milliseconds (can be seconds in -lang qb, see below) given elapsed (if any value was passed) or until the user presses a key. If amount is below 100 ms then Sleep will always wait the full requested amount (key presses are ignored).

Include the second parameter, 1, for a "deep" sleep, which cannot be interrupted by pressing a key.

The accuracy of Sleep is variable depending on the OS cycle time (Windows NT/2K/XP: 15 ms, 9x/Me: 50 ms, Linux 10ms, DOS 55 ms).

Call Sleep with 25ms or less to release time-slice when waiting for user input or looping inside a thread. This will prevent the program from unnecessarily hogging the CPU.

Sleep does not clear the keyboard buffer and any keys pressed during a call to Sleep are retained and can be read using Inkey. In order to wait for a key press, and remove the key from the buffer, Getkey can be used instead.

Examples:
Print "press a key"
Sleep
GetKey 'clear the keyboard buffer
Print "waiting half second"
Sleep 500


Dialect Differences:
Differences from QB:
See also:
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