SHARED

From QB64 Phoenix Edition Wiki
Jump to navigation Jump to search

The SHARED statement allows variables to be passed automatically to any SUB or FUNCTION procedure.


Syntax

DIM SHARED Qt AS STRING * 1


  • DIMensioned variables are shared with all procedures in the program module.
  • When used with DIM in the main module, it eliminates the need to pass a parameter variable to a SUB or FUNCTION.
  • Use COMMON SHARED to share a list of variable values with sub-procedures or other modules. See also: COMMON
  • SHARED (without DIM) can share a list of variables inside of SUB or FUNCTION procedures with the main module only.
Note: SHARED variables in sub-procedures will not be passed to other sub-procedures, only the main module.


Example 1: Defining variable types with AS or type suffixes.

DIM SHARED Qt AS STRING * 1, price AS DOUBLE, ID AS INTEGER
DIM SHARED Q$, prices#, IDs%


Example 2: The DIR$ function returns a filename or a list when more than one exist. The file spec can use a path and/or wildcards.

FOR i = 1 TO 2
  LINE INPUT "Enter a file spec: ", spec$
  file$ = DIR$(spec$)        'use a file spec ONCE to find the last file name listed
  PRINT DIRCount%, file$,    'function can return the file count using SHARED variable
  DO
    K$ = INPUT$(1)
    file$ = DIR$("")         'use an empty string parameter to return a list of files!
    PRINT file$,
  LOOP UNTIL LEN(file$) = 0  'file list ends with an empty string
NEXT
END

FUNCTION DIR$ (spec$)
CONST TmpFile$ = "DIR$INF0.INF", ListMAX% = 500  'change maximum to suit your needs
SHARED DIRCount%                                 'returns file count if desired
STATIC Ready%, Index%, DirList$()
IF NOT Ready% THEN REDIM DirList$(ListMax%): Ready% = -1  'DIM array first use
IF spec$ > "" THEN                               'get file names when a spec is given
  SHELL _HIDE "DIR " + spec$ + " /b > " + TmpFile$
  Index% = 0: DirList$(Index%) = "": ff% = FREEFILE
  OPEN TmpFile$ FOR APPEND AS #ff%
  size& = LOF(ff%)
  CLOSE #ff%
  IF size& = 0 THEN KILL TmpFile$: EXIT FUNCTION
  OPEN TmpFile$ FOR INPUT AS #ff%
  DO WHILE NOT EOF(ff%) AND Index% < ListMAX%
    Index% = Index% + 1
    LINE INPUT #ff%, DirList$(Index%)
  LOOP
  DIRCount% = Index%                       'SHARED variable can return the file count
  CLOSE #ff%
  KILL TmpFile$
ELSE IF Index% > 0 THEN Index% = Index% - 1 'no spec sends next file name
END IF
DIR$ = DirList$(Index%)
END FUNCTION
Code by Ted Weissgerber
Explanation: The SHARED variable value DIRcount% can tell the main program how many files were found using a wildcard spec.


See also



Navigation:
Main Page with Articles and Tutorials
Keyword Reference - Alphabetical
Keyword Reference - By usage