# STATIC

The STATIC keyword is used in declaration statements to control where variables are stored.

## Syntax

## Syntax

## Description

- A STATIC list can be used in SUB and FUNCTION procedures to designate one or more variables to retain their values.
- Variables and arrays with static storage will retain their values in between procedure calls. The values may also be used recursively.

- STATIC can be used after the name of a SUB or FUNCTION in the procedure to force all variables to retain their values.
**Recursive procedures may be required to be STATIC to avoid a Stack Overflow error. QB64 programs may just close.**- $STATIC defined program arrays cannot be re-sized or use _PRESERVE.

*Example 1: Finding the binary bit settings from a 32 bit LONG register return using recursion.*

* *
INPUT "Enter a numerical value to see binary value: ", num&
PRINT Bin$(num&)
END
FUNCTION Bin$ (n&) STATIC 'comment out STATIC to see what happens!
DIM p%, s$
IF 2 ^ p% > n& THEN
p% = 0
ELSE
IF n& AND 2 ^ p% THEN s$ = "1" + s$ ELSE s$ = "0" + s$
IF n& > 2 ^ p% THEN
p% = p% + 1
s$ = Bin$(n&) 'recursive call to itself
ELSE: p% = 0
END IF
END IF
IF s$ = "" THEN Bin$ = "0" ELSE Bin$ = s$
END FUNCTION * *

*Explanation:*The FUNCTION above returns a STRING value representing the bits ON in an INTEGER value. The string can be printed to the screen to see what is happening in a port register.**STATIC**keeps the function from overloading the memory "Stack" and is normally REQUIRED when recursive calls are used in QBasic!**QB64 procedures will close without warning or error!**

*Example 2:* Using a static array to cache factorials, speeding up repeated calculations:

PRINT Factorial(0) PRINT Factorial(5) PRINT Factorial(50) FUNCTION Factorial# ( n AS DOUBLE ) CONST maxNToCache = 50 STATIC resultCache() AS DOUBLE STATIC firstCall AS INTEGER ' The lookup table is initially empty, so re-size it.. IF firstCall = 0 THEN firstCall = -1 REDIM resultCache(maxNToCache) AS DOUBLE ' ..and pre-calculate some factorials. resultCache(0) = 1 resultCache(1) = 1 resultCache(2) = 2 END IF ' See if we have the result cached. If so, we're done. IF n <= maxNToCache THEN IF resultCache(n) <> 0 THEN Factorial = resultCache(n) EXIT FUNCTION END IF END IF ' If not, we use recursion to calculate the result, then cache it for later use: resultCache(n) = INT(n) * Factorial(INT(n) - 1) Factorial = resultCache(n) END FUNCTION

1 120 3.041409320171338D+64

## See also

*Navigation:*