mirror of
https://github.com/QB64-Phoenix-Edition/QB64pe.git
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6e01fc8dce
Added new _STRCMP and _STRICMP commands for quick string comparisons. Cleaned up QB64 to finish removing the QUI (quick user insert) code and folders. Altered UCASE and LCASE routines to be faster in some situations for us.
78 lines
3.9 KiB
Plaintext
78 lines
3.9 KiB
Plaintext
'''VARPTR$''' is a memory function that returns a [[STRING]] representation of a variable's memory address value for use in a [[DRAW]] or [[PLAY]] statement.
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{{PageSyntax}}
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:: string_value$ = VARPTR$(''variable'')
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* Can use any [[STRING|string]] or numerical variable reference '''existing''' in memory.
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* If the parameter value is from an array it must be dimensioned already. Cannot use fixed length string arrays.
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* When using '''numerical''' ''variable'' values in [[DRAW]] strings, use an = sign after the function letter. "TA=" + VARPTR$(''variable%'')
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* Always use variable X as in "X" + VARPTR$(''string_variable$'') to [[DRAW]] or [[PLAY]] another [[STRING]] value.
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* DRAW relative Moves use a + or - before the equal sign. EX: DRAW "M+=" + VARPTR$(x%) + ",-=" + VARPTR$(y%)
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''Example 1:'' How VARPTR$ reads consecutive values from memory.
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{{CodeStart}} '' ''
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{{Cl|SCREEN (statement)|SCREEN}} 2
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{{Cl|CLS}}
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WIND$ = "r10 d7 l10 u7 br20" 'create draw string to be read by function
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ROW$ = "x"+{{Cl|VARPTR$}}(WIND$)+"x"+{{Cl|VARPTR$}}(WIND$)+"x"+{{Cl|VARPTR$}}(WIND$)+" x"+{{Cl|VARPTR$}}(WIND$)+"bl80 bd11"
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{{Cl|LINE}} (100, 50)-(200, 160), , B
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{{Cl|DRAW}} "bm 115,52"
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{{Cl|FOR...NEXT|FOR}} I = 1 {{Cl|TO}} 10
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{{Cl|DRAW}} "x" + {{Cl|VARPTR$}}(ROW$)
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{{Cl|NEXT}} '' ''
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{{CodeEnd}}
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:''NOTE:'' '''GWBasic''' allows '''semicolons''' to be used in the ROW$ definition, but Qbasic and '''QB64''' MUST use '''+''' concatenation.
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''Example 2:'' Using the function to change a Turn Angle value using DRAW.
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{{CodeStart}} '' ''
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{{Cl|SCREEN (statement)|SCREEN}} 12
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'Demonstrates how string DRAW angles are used with TA
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{{Cl|FOR...NEXT|FOR}} i = 0 {{Cl|TO}} 360 {{Cl|STEP}} 30 'mark clock hours every 30 degrees
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angle$ = {{Cl|STR$}}(i) 'change degree value i to a string
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{{Cl|PSET}} (175, 250), 6 'clock center
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{{Cl|DRAW}} "TA" + angle$ + "BU100" 'add string angle to Turn Angle and draw blind up
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{{Cl|CIRCLE}} {{Cl|STEP}}(0, 0), 5, 12 'place a circle at end of Up line
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{{Cl|DRAW}} "P9, 12"
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{{Cl|_DELAY}} .5
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{{Cl|NEXT}}
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'Demonstrates how VARPTR$ is used with TA=
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{{Cl|DO}}: sec$ = {{Cl|RIGHT$}}({{Cl|TIME$}}, 2) 'get current second value from time
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degree = {{Cl|VAL}}(sec$) * -6 'use a negative value to Turn Angle clockwise
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{{Cl|PSET}} (175, 250), 9 'clock center
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{{Cl|DRAW}} "TA=" + {{Cl|VARPTR$}}(degree) + "U90" 'VARPTR$ value requires = in DRAW
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{{Cl|DO}}: {{Cl|_LIMIT}} 30: {{Cl|LOOP}} {{Cl|UNTIL}} {{Cl|RIGHT$}}({{Cl|TIME$}}, 2) <> sec$ 'loop until seconds value changes
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{{Cl|IF}} {{Cl|INKEY$}} <> "" {{Cl|THEN}} {{Cl|EXIT DO}}
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{{Cl|PSET}} (175, 250), 0
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{{Cl|DRAW}} "TA=" + {{Cl|VARPTR$}}(degree) + "U90" 'erase previous second hand draw
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{{Cl|LOOP}} '' ''
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{{CodeEnd}}
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:''Explanation:'' When the VARPTR$ value is used in DRAW, '''=''' MUST be used to pass the value to the draw! Negative Turn Angle values move clockwise and each second moves the hand 6 degrees. '''TA''' uses actual degree angles starting at 0 or noon.
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''Example 3:'' Comparing DRAW moves using VARPTR$ and [[STR$]] values.
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{{CodeStart}} '' ''
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{{Cl|SCREEN}} 12
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{{Cl|PSET}} (200, 200), 12
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{{Cl|CIRCLE}} {{Cl|STEP}}(0, 0), 5, 10
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A = 100: B = 100
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{{Cl|DRAW}} "M+=" + {{Cl|VARPTR$}}(A) + ",-=" + {{Cl|VARPTR$}}(B)
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{{Cl|PSET}} (400, 400), 10
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{{Cl|CIRCLE}} {{Cl|STEP}}(0, 0), 5, 12
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C = 100: D = -100
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{{Cl|DRAW}} "M+" + {{Cl|STR$}}(C) + "," + {{Cl|STR$}}(D) 'must add + for positive relative moves
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{{Cl|END}} '' ''
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{{CodeEnd}}
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: ''Explanation:'' A negative STR$ value will move the DRAW relatively where VARPTR$ won't without the sign before the equal.
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''See also:''
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* [[VARPTR]], [[STR$]]
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* [[DRAW]], [[PLAY]]
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{{PageNavigation}} |