RANDOMIZE statement

Purpose:

RANDOMIZE initializes the RND function random number generator.

RANDOMIZE([Number])

Example:

The following code shows how to generate a cryptographically secure seed Number for the RANDOMIZE function.

 DIM AS DOUBLE Random
 DIM AS DOUBLE TheSeed
 DIM AS INTEGER i, j
 
 TheSeed = CryptoSeed()
 
 PUSHCOLORS
 
 CLS
 COLOR 2, 0 : LOCATE 12, 25, 0
 INPUT "Hit [Enter] to see a sample", i : COLOR 7, 0
 CLS
 RANDOMIZE(TheSeed)
 FOR i = 1 TO 23
   FOR j = 1 TO 70 STEP 20
     Random = RND
     LOCATE i, j, 0
     COLOR MOD(i, 4.0) + 10, 0
     PRINT Random
   NEXT
 NEXT
 LOCATE i, j
 COLOR 7, j
 
 FUNCTION CryptoSeed AS DOUBLE
 
   STATIC AS HCRYPTPROV hProv
   STATIC AS INTEGER isInit
   DIM AS UINT n
   DIM AS INTEGER ok
 
   IF isInit = 0 THEN
     ok = CryptAcquireContext(&hProv, NULL, NULL, PROV_RSA_FULL, CRYPT_VERIFYCONTEXT)
     IF ok = FALSE  THEN FUNCTION = -1
     isInit = 1
   END IF
 
   ' Cast &n to BYTE* so it works with CryptGenRandom 
   ok = CryptGenRandom(hProv, SIZEOF(n), (BYTE*)&n)
   IF ok = FALSE THEN FUNCTION = -1
 
   FUNCTION = CAST(DOUBLE, n / 4294967296.0)
 END FUNCTION
 
 POPCOLORS
 
 PAUSE
 

Remarks:

The above code can be considered FIPS-compliant when run on a properly configured system with a validated provider. On Windows, configuration can be enabled via Local Security Policy. For more information, visit the
Microsoft System cryptography: Use FIPS compliant algorithms for encryption, hashing, and signing webpage

BCX Console Sample Programs using the RANDOMIZE function.

• S95.bas
• S135.bas

RND function

Purpose:

RND returns, as a single precision float, a random value between 0.0 and 1.0.

RetVal = RND

Example:

RangeR.bas will emit a single precision float between the LowValue and HighValue entered on the command line.

' RangeR.bas
' Usage: RangeR LowValue HighValue RandomizerValue

DIM RetVal!
DIM hi!, lo!, rz!

lo! = VAL(COMMAND$(1))
hi! = VAL(COMMAND$(2))
rz! = VAL(COMMAND$(3))

IF rz! = 0.0 THEN
  RANDOMIZE
ELSE
  RANDOMIZE(rz!)
END IF

FOR INTEGER i = 1 TO 6
  RetVal! = RangeR(lo!, hi!)
  PRINT RetVal!
NEXT i

FUNCTION RangeR! (low!, high!)
 
  IF (low! > high!) THEN
    DIM t!
    t! = low!
    low! = high!
    high! = t!
  END IF
   
  FUNCTION = (high! - low! + 1) * RND + low!

END FUNCTION

Result:

C:\Dev\BCX>RangeR 9 27 13
21.05748
19.64941
9.756275
14.62314
17.23507
22.13492

BCX Console Sample Programs using the RND function.

• S95.bas
• S107.bas
• S111.bas
• S135.bas

RND2 function

Purpose:

RND2 returns, as a DOUBLE, a random value in a range between a specified lower and upper value. Lesser precision arguments, INTEGER, LONG, SINGLE are allowed.

RetVal = RND2(LowerNumber AS DOUBLE, UpperNumber AS DOUBLE)

Example:

$BCXVERSION "8.2.2"

DIM RetVal#

RANDOMIZE TIMER

FOR INTEGER i = 1 TO 6
  RetVal# = RND2(10.0, 11.0)
  PRINT RetVal#
NEXT i%

PAUSE

Result:

10.6598205566406
10.9359741210938
11
10.666015625
10.8933410644531
10.6361999511719

Press any key to continue . . .