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50 lines
2 KiB
Text
50 lines
2 KiB
Text
The [[CVD]] function decodes an 8-byte [[STRING]] generated by [[MKD$]] (or read from a file) to [[DOUBLE]] numeric values.
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{{PageSyntax}}
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: {{Parameter|result#}} = [[CVD]]({{Parameter|stringData$}})
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{{PageDescription}}
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* ''CV'' functions ([[CVD]], [[CVS]], [[CVI]], [[CVL]], [[CVDMBF]], [[CVSMBF]]) are used to convert values encoded by ''MK$'' functions ([[MKD$]], [[MKS$]], [[MKI$]], [[MKL$]], [[MKDMBF$]], [[MKSMBF$]]).
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* Variables of numerical types are also encoded when [[PUT]] to a [[RANDOM]] or [[BINARY]]-access file.
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* '''QB64''' has [[_CV]] and [[_MK$]] functions which can also deal with extended [[Data types|data types]].
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* [[DOUBLE]] values can range up to 15 decimal point digits. Decimal point accuracy depends on whole value places taken.
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{{PageExamples}}
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''Example 1:'' Reading an 8-byte encoded string n$ from a file and obtaining the decoded [[DOUBLE]] value:
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{{CodeStart}} '' ''
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{{Cl|FIELD}} #1, 8 {{Cl|AS}} N$, 12 {{Cl|AS}} B$...
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{{Cl|GET}} #1
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Y# = {{Cl|CVD}}(N$) '' ''
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{{CodeEnd}}
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: ''Explanation:'' Reads a field from file #1, and converts the first eight bytes (N$) into an double-precision number assigned to the variable Y#.
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''Example 2:'' Showcases the reduced space to store an encoded number.
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{{CodeStart}}
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a# = 77000.24523213
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{{Cl|PRINT}} "Value of a#:"; a#
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b$ = {{Cl|MKD$}}(a#)
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{{Cl|PRINT}} "Value of a# encoded using MKD$: "; b$
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{{Cl|PRINT}} "The string above, decoded using CVD:"; {{Cl|CVD}}(b$)
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{{CodeEnd}}
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{{OutputStart}}
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Value of a#: 77000.24523213
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Value of a# encoded using MKD$: ñåxýâ╠‗@
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The string above, decoded using CVD: 77000.24523213
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{{OutputEnd}}
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:Since the representation of a double-precision number can use up to 15 ASCII characters (fifteen bytes), writing to a file using [[MKD$]] conversion, and then reading back with the [[CVD]] conversion can save up to 7 bytes of storage space.
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{{PageSeeAlso}}
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{{PageSeeAlso}}
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* [[MKD$]], [[MKI$]], [[MKS$]], [[MKL$]], [[MKDMBF$]], [[MKSMBF$]]
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* [[CVI]], [[CVS]], [[CVL]], [[CVSMBF]], [[CVDMBF]]
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* [[_CV]], [[_MK$]]
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{{PageNavigation}}
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