mirror of
https://github.com/QB64-Phoenix-Edition/QB64pe.git
synced 2024-06-29 10:30:36 +00:00
52 lines
2 KiB
Plaintext
52 lines
2 KiB
Plaintext
The [[CVD]] function decodes an 8-byte [[STRING]] generated by [[MKD$]] (or read from a file) to [[DOUBLE]] numeric values.
|
|
|
|
|
|
{{PageSyntax}}
|
|
: {{Parameter|result#}} = [[CVD]]({{Parameter|stringData$}})
|
|
|
|
|
|
{{PageDescription}}
|
|
* ''CV'' functions ([[CVD]], [[CVS]], [[CVI]], [[CVL]], [[CVDMBF]], [[CVSMBF]]) are used to convert values encoded by ''MK$'' functions ([[MKD$]], [[MKS$]], [[MKI$]], [[MKL$]], [[MKDMBF$]], [[MKSMBF$]]).
|
|
* Variables of numerical types are also encoded when [[PUT]] to a [[RANDOM]] or [[BINARY]]-access file.
|
|
* '''QB64''' has [[_CV]] and [[_MK$]] functions which can also deal with extended [[Data types|data types]].
|
|
* [[DOUBLE]] values can range up to 15 decimal point digits. Decimal point accuracy depends on whole value places taken.
|
|
|
|
|
|
{{PageExamples}}
|
|
''Example 1:'' Reading an 8-byte encoded string n$ from a file and obtaining the decoded [[DOUBLE]] value:
|
|
{{CodeStart}} '' ''
|
|
{{Cl|FIELD}} #1, 8 {{Cl|AS}} N$, 12 {{Cl|AS}} B$...
|
|
{{Cl|GET}} #1
|
|
Y# = {{Cl|CVD}}(N$) '' ''
|
|
{{CodeEnd}}
|
|
: ''Explanation:'' Reads a field from file #1, and converts the first eight bytes (N$) into an double-precision number assigned to the variable Y#.
|
|
|
|
|
|
''Example 2:'' Showcases the reduced space to store an encoded number.
|
|
{{CodeStart}}
|
|
a# = 77000.24523213
|
|
{{Cl|PRINT}} "Value of a#:"; a#
|
|
b$ = {{Cl|MKD$}}(a#)
|
|
{{Cl|PRINT}} "Value of a# encoded using MKD$: "; b$
|
|
{{Cl|PRINT}} "The string above, decoded using CVD:"; {{Cl|CVD}}(b$)
|
|
{{CodeEnd}}
|
|
{{OutputStart}}
|
|
Value of a#: 77000.24523213
|
|
|
|
Value of a# encoded using MKD$: ñåxýâ╠‗@
|
|
|
|
The string above, decoded using CVD: 77000.24523213
|
|
{{OutputEnd}}
|
|
:Since the representation of a double-precision number can use up to 15 ASCII characters (fifteen bytes), writing to a file using [[MKD$]] conversion, and then reading back with the [[CVD]] conversion can save up to 7 bytes of storage space.
|
|
|
|
|
|
{{PageSeeAlso}}
|
|
{{PageSeeAlso}}
|
|
* [[MKD$]], [[MKI$]], [[MKS$]], [[MKL$]], [[MKDMBF$]], [[MKSMBF$]]
|
|
* [[CVI]], [[CVS]], [[CVL]], [[CVSMBF]], [[CVDMBF]]
|
|
* [[_CV]], [[_MK$]]
|
|
|
|
|
|
{{PageNavigation}}
|
|
<
|