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106 lines
3.7 KiB
Plaintext
106 lines
3.7 KiB
Plaintext
'''RANDOMIZE''' is used with a seed value to generate different random number sequences using the [[RND]] function.
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{{PageSyntax}}
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:: '''RANDOMIZE''' [USING] '''{''seednumber''|TIMER}'''
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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.
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* If the ''seed number'' is omitted, the program will display: '''Random-number seed (-32768 to 32767)?''' request on screen.
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* '''USING''' resets a ''seed number'' sequence to the start of the sequence as if the program just started using that seed in '''QB64 only'''.
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* '''Note:''' The RANDOMIZE USING ''seed number'' MUST be designated or a {{text|Name already in use|blue}} status error will occur!
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* If the same initial seed number is used, the sequence of random numbers returned will be identical every program run.
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* The fact that random numbers would always be the same has been used for simple data encryption and decryption.
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* Using a [[TIMER]] starting value ensures that the initial return sequence values are different almost every time the program is run!
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* [[RUN]] should reset the [[RANDOMIZE]] sequence to the starting [[RND]] function value.(Not yet in QB64)
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''Example 1:'' Using RANDOMIZE '''TIMER''' to set a different starting sequence of [[RND|random]] numbers every run.
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{{CodeStart}}{{Cl|RANDOMIZE}} {{Cl|TIMER}}
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{{Cl|DO...LOOP|DO}}
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randnum% = INT({{Cl|RND}} * 11) + 2 'add one to multiplier as INT rounds down and never equals 10
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PRINT randnum%
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K$ = {{Cl|INPUT$}}(1)
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{{Cl|LOOP}} {{Cl|UNTIL}} {{Cl|UCASE$}}(K$) = "Q" 'q = quit
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{{Cl|END}} '' ''
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{{CodeEnd}}
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:''Explanation:'' Procedure generates random integer values from 2 to 12 like a pair of dice.
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''Example 2:'' Repeating a random number sequence with RANDOMIZE '''USING''' and a specific seed value in '''QB64''' only.
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{{CodeStart}}seed = 10
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{{Cl|RANDOMIZE}} seed
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Print7
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{{Cl|RANDOMIZE}} seed
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Print7
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{{Cl|PRINT}} "Press a key to start sequence over!"
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K$ = {{Cl|INPUT$}}(1)
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{{Cl|RANDOMIZE}} '''USING''' seed
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Print7
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{{Cl|SUB}} Print7
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{{Cl|FOR...NEXT|FOR}} r = 1 TO 7
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{{Cl|PRINT}} {{Cl|RND}};
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{{Cl|NEXT}}
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{{Cl|PRINT}}: {{Cl|PRINT}}
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{{Cl|END SUB}} '' ''
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{{CodeEnd}}
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: ''Explanation:'' The second RANDOMIZE statement just continues the sequence where USING in the third restarts the sequence.
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''Example 3:'' Random fireworks explosions:
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{{CodeStart}}{{Cl|RANDOMIZE}} {{Cl|TIMER}}
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{{Cl|DEFINT}} A-Z
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{{Cl|TYPE}} ftype
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vx {{Cl|AS}} {{Cl|SINGLE}}
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vy {{Cl|AS}} {{Cl|SINGLE}}
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{{Cl|END}} {{Cl|TYPE}}
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{{Cl|DIM}} frag(500) {{Cl|AS}} ftype 'fragments
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{{Cl|DIM}} pi {{Cl|AS}} {{Cl|SINGLE}}
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pi = 3.141593
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{{Cl|DIM}} x {{Cl|AS}} {{Cl|SINGLE}}, y {{Cl|AS}} {{Cl|SINGLE}}
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{{Cl|DIM}} t {{Cl|AS}} {{Cl|SINGLE}}, g {{Cl|AS}} {{Cl|SINGLE}}, p {{Cl|AS}} {{Cl|SINGLE}}
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t = 0
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g = 0.4 'gravity
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p = 15 'explosion power
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sw = 800
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sh = 600
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{{Cl|SCREEN}} {{Cl|_NEWIMAGE}}(sw, sh, 32)
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DO
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{{Cl|FOR...NEXT|FOR}} i = 0 {{Cl|TO}} {{Cl|UBOUND}}(frag)
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frag(i).vx = {{Cl|RND}} * {{Cl|COS}}(2 * pi * {{Cl|RND}})
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frag(i).vy = {{Cl|RND}} * {{Cl|SIN}}(2 * pi * {{Cl|RND}})
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{{Cl|NEXT}}
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x = sw * {{Cl|RND}}
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y = sh * {{Cl|RND}}
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{{Cl|FOR...NEXT|FOR}} t = 0 {{Cl|TO}} 25 {{Cl|STEP}} 0.1
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{{Cl|LINE}} (0, 0)-(sw, sh), {{Cl|_RGB}}(0, 0, 0), BF
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{{Cl|FOR...NEXT|FOR}} i = 0 {{Cl|TO}} {{Cl|UBOUND}}(frag)
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{{Cl|PSET}} (x + t * p * frag(i).vx, y + t * p * frag(i).vy + g * t * t), {{Cl|_RGB}}(255, 255, 0)
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{{Cl|NEXT}}
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{{Cl|_DISPLAY}}
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{{Cl|_LIMIT}} 150
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{{Cl|IF...THEN|IF}} {{Cl|_KEYHIT}} = -27 {{Cl|THEN}} {{Cl|EXIT DO}}
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{{Cl|NEXT}}
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{{Cl|LOOP}}
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{{Cl|SYSTEM}}
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{{CodeEnd}}{{small|Code by Ben}}
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''See also:''
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* [[RND]], [[INT]], [[CINT]]
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* [[TIMER]]
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{{PageNavigation}}
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