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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.
68 lines
3.5 KiB
Plaintext
68 lines
3.5 KiB
Plaintext
The '''CVI''' function converts 2 byte [[GET]] or [[MKI$]] [[STRING]] values to [[INTEGER]] numeric values.
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::::::''Syntax:'' CVI(''2-byte string'')
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* Numeric values read from a [[RANDOM]]-access or [[BINARY]] disk file must be converted from [[ASCII]] string characters back into numbers if they are to be arithmetically manipulated.
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* [[INTEGER]] values can range from -32768 to 32767.
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* [[CVI]] converts a 2-byte string created by [[MKI$]] to an [[INTEGER]] numerical value.
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* [[CVL]] converts a 4 byte string created by [[MKL$]] to a [[LONG]] integer numerical value.
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* [[CVS]] converts a 4-byte string created by [[MKS$]] to a [[SINGLE]]-precision numerical value.
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* [[CVD]] converts an 8-byte string created by [[MKD$]] to a [[DOUBLE]]-precision numerical value.
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* CV functions can only be used to convert values from [[MK$]] string function values or data from [[BINARY]] files!
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''Example 1:''
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{{CodeStart}} '' ''
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{{Cl|FIELD}} #1, 2 {{Cl|AS}} N$, 12 {{Cl|AS}} B$...
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{{Cl|GET}} #1 'GET does not need a position or variable with successive FIELD buffer reads
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Y = {{Cl|CVI}}(N$) '' ''
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{{CodeEnd}}
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:''Explanation:'' Reads a field from file #1, and converts the first two bytes (N$) into an integer number assigned to the variable Y.
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:Since an integer number can contain as many as five ASCII characters (five bytes), writing a file using [[MKI$]] conversion, and reading with the CVI conversion, as many as three bytes per number recorded are saved on the storage medium.
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''Example 2:'' How CVI converts the ASCII code values created by the MKI$ function.
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{{CodeStart}}
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{{Cl|SCREEN (statement)|SCREEN}} 12 '_PRINTSTRING requires a graphic screen mode
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{{Cl|DIM}} Q {{Cl|AS}} {{Cl|STRING}} * 1
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Q = {{Cl|CHR$}}(34)
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' create Print using templates to align the values returned
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tmp1$ = "1st character code = ### * 1 = ### "
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tmp2$ = "2nd character code = ### * 256 = ##### "
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tmp3$ = " & "
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tmp4$ = " CVI Total = ##### "
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{{Cl|DO...LOOP|DO}}
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{{Cl|COLOR}} 14: {{Cl|LOCATE}} 13, 20: {{Cl|INPUT}} "Enter an Integer from 1 to 32767(0 quits): ", number%
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{{Cl|IF...THEN|IF}} number% < 1 {{Cl|THEN}} {{Cl|EXIT DO}}
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{{Cl|CLS}}
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ASCII$ = {{Cl|MKI$}}(number%) ' create the 2 byte character string
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{{Cl|COLOR}} 11
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{{Cl|_PRINTSTRING}} (152, 240), "{{Cl|MKI$}} creates 2 byte ASCII string: " + Q + ASCII$ + Q ' displays character(s)
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asc1% = {{Cl|ASC}}(ASCII$) ' find the ASCII code values of each character
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asc2% = {{Cl|ASC}}(ASCII$, 2) ' '''QB64''' allows ASC to read specific characters in a string
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{{Cl|LOCATE}} 18, 20: {{Cl|PRINT USING}} tmp1$; asc1%; asc1%
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{{Cl|LOCATE}} 19, 20: {{Cl|PRINT USING}} tmp2$; asc2%; asc2% * 256
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{{Cl|LOCATE}} 20, 20: {{Cl|PRINT USING}} tmp3$; "-----"
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{{Cl|LOCATE}} 21, 20: {{Cl|PRINT USING}} tmp4$; asc1% + (256 * asc2%)
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{{Cl|LOOP}}
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{{Cl|SYSTEM}} '' ''
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{{CodeEnd}}
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{{small|Code by Ted Weissgerber}}
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:''Explanation:'' All [[ASCII]] characters can be displayed using [[_PRINTSTRING]] . The routine gets the [[ASCII]] code, which is the actual value needed by [[CVI]]. The first byte code is always between 0 and 255. The second byte can return 0 thru 127 and CVI multiplies that value by 256. This proves that you cannot just feed a string number value to [[CVI]] and get the result desired! "90" = 12345.
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''See also:''
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* [[MKI$]], [[ASC]]
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* [[MKL$]], [[CVL]]
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* [[MKS$]], [[CVS]]
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* [[MKD$]], [[CVD]]
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* [[Bitmaps]]
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{{PageNavigation}} |