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QB64 is a modern extended BASIC programming language that retains QBasic/QuickBASIC 4.5 compatibility and compiles native binaries for Windows, Linux, and macOS.

The CVI function decodes a 2-byte STRING generated by MKI$ (or read from a file) to INTEGER numeric values.

Syntax

result% = CVI(stringData$)

Description

Example(s)

Example 1:


FIELD #1, 2 AS N$, 12 AS B$...
GET #1     'GET does not need a position or variable with successive FIELD buffer reads
Y = CVI(N$) 

Explanation: Reads a field from file #1, and converts the first two bytes (N$) into an integer number assigned to the variable Y. Since the representation of an integer number can use up to 5 ASCII characters (five bytes), writing to a file using MKI$ conversion, and then reading back with the CVI conversion can save up to 3 bytes of storage space.

How CVI converts the ASCII code values created by the MKI$ function.


SCREEN 12
DIM Q AS STRING * 1
Q = CHR$(34)
' create Print using templates to align the values returned 
tmp1$ = "1st character code = ### * 1   =   ### "
tmp2$ = "2nd character code = ### * 256 = ##### "
tmp3$ = "                                 &  "
tmp4$ = "                     CVI Total = ##### "

DO
  COLOR 14: LOCATE 13, 20: INPUT "Enter an Integer from 1 to 32767(0 quits): ", number%
  IF number% < 1 THEN EXIT DO
  CLS
  ASCII$ = MKI$(number%)     ' create the 2 byte character string
  COLOR 11
  _PRINTSTRING (152, 240), "MKI$ creates 2 byte ASCII string: " + Q + ASCII$ + Q ' displays character(s)

  asc1% = ASC(ASCII$)        ' find the ASCII code values of each character
  asc2% = ASC(ASCII$, 2)     ' **QB64** allows ASC to read specific characters in a string
 
  LOCATE 18, 20: PRINT USING tmp1$; asc1%; asc1%
  LOCATE 19, 20: PRINT USING tmp2$; asc2%; asc2% * 256
  LOCATE 20, 20: PRINT USING tmp3$; "-----"
  LOCATE 21, 20: PRINT USING tmp4$; asc1% + (256 * asc2%)
LOOP
SYSTEM 

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” gets decoded to 12345).

See Also