RANDOMIZE: Difference between revisions

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* The ''seed number'' can be ANY positive or negative numerical type value. The [[TIMER]] value is often used to change [[RND]] output each run.
* The ''seed number'' can be ANY positive or negative numerical type value. The [[TIMER (function)|TIMER]] value is often used to change [[RND]] output each run.
* If the ''seed number'' is omitted, the program will display: '''Random-number seed (-32768 to 32767)?''' request on screen.
* If the ''seed number'' is omitted, the program will display: '''Random-number seed (-32768 to 32767)?''' request on screen.
* '''USING''' resets a ''seed number'' sequence to the start of the sequence as if the program just started using that seed in '''QB64 only'''.
* '''USING''' resets a ''seed number'' sequence to the start of the sequence as if the program just started using that seed in '''QB64 only'''.
* '''Note:''' The RANDOMIZE USING ''seed number'' MUST be designated or a {{text|Name already in use|blue}} status error will occur!
* '''Note:''' The RANDOMIZE USING ''seed number'' MUST be designated or a {{Text|Name already in use|blue}} status error will occur!
* If the same initial seed number is used, the sequence of random numbers returned will be identical every program run.
* If the same initial seed number is used, the sequence of random numbers returned will be identical every program run.
* The fact that random numbers would always be the same has been used for simple data encryption and decryption.
* The fact that random numbers would always be the same has been used for simple data encryption and decryption.
* Using a [[TIMER]] starting value ensures that the initial return sequence values are different almost every time the program is run!
* Using a [[TIMER (function)|TIMER]] starting value ensures that the initial return sequence values are different almost every time the program is run!
* [[RUN]] should reset the [[RANDOMIZE]] sequence to the starting [[RND]] function value.(Not yet in QB64)
* [[RUN]] should reset the [[RANDOMIZE]] sequence to the starting [[RND]] function value.(Not yet in QB64)




''Example 1:'' Using RANDOMIZE '''TIMER''' to set a different starting sequence of [[RND|random]] numbers every run.
''Example 1:'' Using RANDOMIZE '''TIMER''' to set a different starting sequence of [[RND|random]] numbers every run.
{{CodeStart}}{{Cl|RANDOMIZE}} {{Cl|TIMER}}
{{CodeStart}}{{Cl|RANDOMIZE}} {{Cl|TIMER (function)|TIMER}}
{{Cl|DO...LOOP|DO}}
{{Cl|DO...LOOP|DO}}
randnum% = INT({{Cl|RND}} * 11) + 2  'add one to multiplier as INT rounds down and never equals 10
randnum% = INT({{Cl|RND}} * 11) + 2  'add one to multiplier as INT rounds down and never equals 10
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''Example 3:'' Random fireworks explosions:
''Example 3:'' Random fireworks explosions:
{{CodeStart}}{{Cl|RANDOMIZE}} {{Cl|TIMER}}
{{CodeStart}}{{Cl|RANDOMIZE}} {{Cl|TIMER (function)|TIMER}}
{{Cl|DEFINT}} A-Z
{{Cl|DEFINT}} A-Z


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{{Cl|LOOP}}
{{Cl|LOOP}}
{{Cl|SYSTEM}}
{{Cl|SYSTEM}}
{{CodeEnd}}{{small|Code by Ben}}
{{CodeEnd}}
{{Small|Code by Ben}}




{{PageSeeAlso}}
{{PageSeeAlso}}
* [[RND]], [[INT]], [[CINT]]
* [[RND]], [[INT]], [[CINT]]
* [[TIMER]]
* [[TIMER (function)]]




{{PageNavigation}}
{{PageNavigation}}

Latest revision as of 17:01, 24 February 2023

RANDOMIZE is used with a seed value to generate different random number sequences using the RND function.


Syntax

RANDOMIZE [USING] {seednumber|TIMER}


  • The seed number can be ANY positive or negative numerical type value. The TIMER value is often used to change RND output each run.
  • If the seed number is omitted, the program will display: Random-number seed (-32768 to 32767)? request on screen.
  • USING resets a seed number sequence to the start of the sequence as if the program just started using that seed in QB64 only.
  • Note: The RANDOMIZE USING seed number MUST be designated or a Name already in use status error will occur!
  • If the same initial seed number is used, the sequence of random numbers returned will be identical every program run.
  • The fact that random numbers would always be the same has been used for simple data encryption and decryption.
  • Using a TIMER starting value ensures that the initial return sequence values are different almost every time the program is run!
  • RUN should reset the RANDOMIZE sequence to the starting RND function value.(Not yet in QB64)


Example 1: Using RANDOMIZE TIMER to set a different starting sequence of random numbers every run. 

RANDOMIZE TIMER
DO
randnum% = INT(RND * 11) + 2  'add one to multiplier as INT rounds down and never equals 10
PRINT randnum%
K$ = INPUT$(1)
LOOP UNTIL UCASE$(K$) = "Q"  'q = quit
END
Explanation: Procedure generates random integer values from 2 to 12 like a pair of dice.


Example 2: Repeating a random number sequence with RANDOMIZE USING and a specific seed value in QB64 only. 

seed = 10
RANDOMIZE seed
Print7
RANDOMIZE seed
Print7
PRINT "Press a key to start sequence over!"
K$ = INPUT$(1)
RANDOMIZE USING seed
Print7

SUB Print7
FOR r = 1 TO 7
  PRINT RND;
NEXT
PRINT: PRINT
END SUB
Explanation: The second RANDOMIZE statement just continues the sequence where USING in the third restarts the sequence.


Example 3: Random fireworks explosions: 

RANDOMIZE TIMER
DEFINT A-Z

TYPE ftype
    vx AS SINGLE
    vy AS SINGLE
END TYPE
DIM frag(500) AS ftype 'fragments

DIM pi AS SINGLE
pi = 3.141593

DIM x AS SINGLE, y AS SINGLE
DIM t AS SINGLE, g AS SINGLE, p AS SINGLE
t = 0
g = 0.4 'gravity
p = 15 'explosion power

sw = 800
sh = 600

SCREEN _NEWIMAGE(sw, sh, 32)

DO
    FOR i = 0 TO UBOUND(frag)
        frag(i).vx = RND * COS(2 * pi * RND)
        frag(i).vy = RND * SIN(2 * pi * RND)
    NEXT

    x = sw * RND
    y = sh * RND

    FOR t = 0 TO 25 STEP 0.1
        LINE (0, 0)-(sw, sh), _RGB(0, 0, 0), BF
        FOR i = 0 TO UBOUND(frag)
            PSET (x + t * p * frag(i).vx, y + t * p * frag(i).vy + g * t * t), _RGB(255, 255, 0)
        NEXT
        _DISPLAY
        _LIMIT 150

        IF _KEYHIT = -27 THEN EXIT DO
    NEXT
LOOP
SYSTEM
Code by Ben


See also


Navigation:
Main Page with Articles and Tutorials
Keyword Reference - Alphabetical
Keyword Reference - By usage
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