CVL: Difference between revisions
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(Created page with "The CVL function decodes a 4-byte STRING generated by MKL$ (or read from a file) to LONG numeric values. {{PageSyntax}} : {{Parameter|result&}} = CVL({{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$, MKSMBF$). * '''QB64''' has _CV and _MK$ functions wh...") |
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{{PageExamples}} | {{PageExamples}} | ||
''Example 1: 4 byte [[ASCII]] character strings show how CVL multipliers convert [[MKL$]] values into a 4 byte [[LONG]] value. | ''Example 1: 4 byte [[ASCII]] character strings show how CVL multipliers convert [[MKL$]] values into a 4 byte [[LONG]] value. | ||
{{CodeStart}} | {{CodeStart}} | ||
{{Cl|PRINT}} {{Cl|CVL}}({{Cl|CHR$}}(1) + {{Cl|STRING$}}(3, 0)) '{{Cl|ASC}}(CHR$(1)) * 1 = 1 | {{Cl|PRINT}} {{Cl|CVL}}({{Cl|CHR$}}(1) + {{Cl|STRING$}}(3, 0)) '{{Cl|ASC}}(CHR$(1)) * 1 = 1 | ||
{{Cl|PRINT}} {{Cl|CVL}}({{Cl|CHR$}}(0) + {{Cl|CHR$}}(1) + {{Cl|STRING$}}(2, 0)) '{{Cl|ASC}}(CHR$(1)) * 256 = 256 | {{Cl|PRINT}} {{Cl|CVL}}({{Cl|CHR$}}(0) + {{Cl|CHR$}}(1) + {{Cl|STRING$}}(2, 0)) '{{Cl|ASC}}(CHR$(1)) * 256 = 256 | ||
{{Cl|PRINT}} {{Cl|CVL}}({{Cl|STRING$}}(2, 0) + {{Cl|CHR$}}(1) + {{Cl|CHR$}}(0)) '{{Cl|ASC}}(CHR$(1)) * 256 * 256 = 65536 | {{Cl|PRINT}} {{Cl|CVL}}({{Cl|STRING$}}(2, 0) + {{Cl|CHR$}}(1) + {{Cl|CHR$}}(0)) '{{Cl|ASC}}(CHR$(1)) * 256 * 256 = 65536 | ||
{{Cl|PRINT}} {{Cl|CVL}}({{Cl|STRING$}}(3, 0) + {{Cl|CHR$}}(1)) '{{Cl|ASC}}(CHR$(1)) * 256 * 256 * 256 = 16777216 | {{Cl|PRINT}} {{Cl|CVL}}({{Cl|STRING$}}(3, 0) + {{Cl|CHR$}}(1)) '{{Cl|ASC}}(CHR$(1)) * 256 * 256 * 256 = 16777216 | ||
{{CodeEnd}} | {{CodeEnd}} | ||
''Example 2:'' | ''Example 2:'' | ||
{{CodeStart}} | {{CodeStart}} | ||
{{Cl|FIELD}} #1, 4 {{Cl|AS}} N$, 12 {{Cl|AS}} B$... | {{Cl|FIELD}} #1, 4 {{Cl|AS}} N$, 12 {{Cl|AS}} B$... | ||
{{Cl|GET}} #1 | {{Cl|GET}} #1 | ||
Y& = {{Cl|CVL}}(N$) | Y& = {{Cl|CVL}}(N$) | ||
{{CodeEnd}} | {{CodeEnd}} | ||
:''Explanation:'' Reads a field from file #1, and converts the first four bytes (N$) into a long integer value assigned to the variable Y&. | :''Explanation:'' Reads a field from file #1, and converts the first four bytes (N$) into a long integer value assigned to the variable Y&. | ||
Revision as of 01:21, 23 January 2023
The CVL function decodes a 4-byte STRING generated by MKL$ (or read from a file) to LONG numeric values.
Syntax
- result& = CVL(stringData$)
Description
- CV functions (CVD, CVS, CVI, CVL, CVDMBF, CVSMBF) are used to convert values encoded by MK$ functions (MKD$, MKS$, MKI$, MKL$, MKDMBF$, MKSMBF$).
- QB64 has _CV and _MK$ functions which can also deal with extended data types.
- LONG values can range from -2147483648 to 2147483647.
- Doesn't return _UNSIGNED values.
Examples
Example 1: 4 byte ASCII character strings show how CVL multipliers convert MKL$ values into a 4 byte LONG value.
PRINT CVL(CHR$(1) + STRING$(3, 0)) 'ASC(CHR$(1)) * 1 = 1 PRINT CVL(CHR$(0) + CHR$(1) + STRING$(2, 0)) 'ASC(CHR$(1)) * 256 = 256 PRINT CVL(STRING$(2, 0) + CHR$(1) + CHR$(0)) 'ASC(CHR$(1)) * 256 * 256 = 65536 PRINT CVL(STRING$(3, 0) + CHR$(1)) 'ASC(CHR$(1)) * 256 * 256 * 256 = 16777216 |
Example 2:
FIELD #1, 4 AS N$, 12 AS B$... GET #1 Y& = CVL(N$) |
- Explanation: Reads a field from file #1, and converts the first four bytes (N$) into a long integer value assigned to the variable Y&.
- 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.
See also