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44 lines
1.9 KiB
Plaintext
44 lines
1.9 KiB
Plaintext
The [[CVL]] function decodes a 4-byte [[STRING]] generated by [[MKL$]] (or read from a file) to [[LONG]] numeric values.
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{{PageSyntax}}
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: {{Parameter|result&}} = [[CVL]]({{Parameter|stringData$}})
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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$]]).
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* '''QB64''' has [[_CV]] and [[_MK$]] functions which can also deal with extended [[Data types|data types]].
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* [[LONG]] values can range from -2147483648 to 2147483647.
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* Doesn't return [[_UNSIGNED]] values.
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{{PageExamples}}
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''Example 1: 4 byte [[ASCII]] character strings show how CVL multipliers convert [[MKL$]] values into a 4 byte [[LONG]] value.
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{{CodeStart}} '' ''
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{{Cl|PRINT}} {{Cl|CVL}}({{Cl|CHR$}}(1) + {{Cl|STRING$}}(3, 0)) '{{Cl|ASC}}(CHR$(1)) * 1 = 1
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{{Cl|PRINT}} {{Cl|CVL}}({{Cl|CHR$}}(0) + {{Cl|CHR$}}(1) + {{Cl|STRING$}}(2, 0)) '{{Cl|ASC}}(CHR$(1)) * 256 = 256
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{{Cl|PRINT}} {{Cl|CVL}}({{Cl|STRING$}}(2, 0) + {{Cl|CHR$}}(1) + {{Cl|CHR$}}(0)) '{{Cl|ASC}}(CHR$(1)) * 256 * 256 = 65536
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{{Cl|PRINT}} {{Cl|CVL}}({{Cl|STRING$}}(3, 0) + {{Cl|CHR$}}(1)) '{{Cl|ASC}}(CHR$(1)) * 256 * 256 * 256 = 16777216 '' ''
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{{CodeEnd}}
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''Example 2:''
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{{CodeStart}} '' ''
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{{Cl|FIELD}} #1, 4 {{Cl|AS}} N$, 12 {{Cl|AS}} B$...
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{{Cl|GET}} #1
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Y& = {{Cl|CVL}}(N$) '' ''
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{{CodeEnd}}
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:''Explanation:'' Reads a field from file #1, and converts the first four bytes (N$) into a long integer value assigned to the variable Y&.
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:Since the representation of a long number can use up to 10 ASCII characters (ten bytes), writing to a file using [[MKL$]] conversion, and then reading back with the [[CVL]] conversion can save up to 6 bytes of storage space.
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{{PageSeeAlso}}
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* [[MKD$]], [[MKI$]], [[MKS$]], [[MKL$]], [[MKDMBF$]], [[MKSMBF$]]
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* [[CVI]], [[CVS]], [[CVD]], [[CVDMBF]], [[CVSMBF]]
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* [[_CV]], [[_MK$]]
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{{PageNavigation}}
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