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.
Example
`
Print "press a key"
Sleep
GetKey 'clear the keyboard buffer
Print "waiting half second"
Sleep 500
`
Dialect Differences

- In the -lang fb and -lang fblite dialects, the `amount` value is in milliseconds.
- In the -lang qb dialect, the `amount` value is in seconds as in QB. If the second parameter `keyflag` is given, or the keyword is written as `__Sleep` the value is expected to be in milliseconds.

Differences from QB

- None in the -lang qb dialect.
- In QB, the delay was given in whole seconds only and did not support the `keyflag` parameter.

See also

- `Timer`
- `Inkey`