Q148689: How to Parse Config.fpw Programmatically

Article: Q148689
Product(s): Microsoft FoxPro
Version(s): 3.00 3.00b
Operating System(s): 
Keyword(s): kbcode
Last Modified: 24-AUG-1999

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The information in this article applies to:

- Microsoft Visual FoxPro for Windows, versions 3.0, 3.0b 
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SUMMARY
=======

This article shows by example how to parse through a text file programmatically.
This example uses Config.fpw. The code searches for a specific entry, and then
it modifies the entry if it is found or adds it if not found.

You might want to use this technique in distributed applications, for example, to
control the operating environment.

MORE INFORMATION
================

This code example checks to determine if the Visual FoxPro system variable
MVCOUNT is less than 2000. If follows this process:

1. Open or Create the Config.fpw file as applicable,

2. Search through the Config.fpw file for the MVCOUNT= entry.

  a. If it finds an entry, it modifies it to read MVCOUNT=2000.

  b. If it doesn't find an entry, it creates one.

3. Write the modified file contents back to disk, and close the file.

Code Sample
-----------

  * Parsefpw.prg
  * ------------
  * To make this backward compatible to FoxPro 2.x, replace the MESSAGEBOX()
  * functions with WAIT WINDOWs
  *
  cNewLine   = "MVCOUNT=2000"+CHR(13)      && This is the line to change/add
  nUpdateStat = 0                          && Use to determine which message
  cVFPConfigLoc = SYS(2019)
  nFileHand   = FOPEN(cVFPConfigLoc, 2)    && open with read/write privileges
  IF nFileHand == -1                       && Can't find Config.fpw
    nFileHand = FCREATE(cVFPConfigLoc, 0)  && Create an Config.fpw
    IF nFileHand == -1                     && Can't create Config.fpw
      = FCLOSE(nFileHand)
      nUpdateStat = 1                      && Not existing, Cannot Create
    ELSE
      = FWRITE(nFileHand, cNewLine)
      = FCLOSE(nFileHand)
      nUpdateStat = 2                      && Not existing, Did Create
    ENDIF
  ELSE
    filesize = FSEEK(nFileHand, 0, 2)
    = FSEEK(nFileHand, 0, 0)               && position file pointer to BOF
    contents = FREAD(nFileHand, filesize)
    spos = RAT("MVCOUNT", UPPER(contents)) && from right to find last
  MVCOUNT

    IF spos <> 0                           && Contains "MVCOUNT" entry
      * len = length (for example, len=20+1=21 for "MVCOUNT = 30 ")
      * len = AT(CHR(13)+CHR(10), SUBSTR(contents, spos)) - 1 && w/o CR & LF
      len = AT(CHR(13)+CHR(10), SUBSTR(contents, spos)) + 1 && with CR & LF
      IF LEN = 0
        LEN = LEN(SUBSTR(contents, spos))
      ENDIF
    ELSE                                   && "MVCOUNT" Not there, append it
      LEN = AT(CHR(26), contents)          && CHR(26) = Escape = EOF marker
      IF LEN <> 0
        contents = LEFT(contents, LEN - 1)
        LEN = 0
      ENDIF
      spos = RAT(CHR(13)+CHR(10), contents, ;
      IIF(RIGHT(contents, 2) <> CHR(13)+CHR(10), 1, 2))
      spos = spos + IIF(spos = 0, 1, 2)
    ENDIF
    contents = STUFF(contents, spos, LEN, cNewLine)
    = FSEEK(nFileHand, 0, 0)
    = FWRITE(nFileHand, contents)
    = FCHSIZE(nFileHand, LEN(contents))
    = FCLOSE(nFileHand)
    nUpdateStat = 3                           && Did exist, Modified
  ENDIF
  ?? CHR(7)
  cMsg1 = "A file named Config.fpw must exist in <YourApp>"+CHR(13);
         +"startup directory. This file must contain an
  MVCOUNT=2000"+CHR(13);
         +"statement in order for the <YourApp> application to
  operate"+CHR(13);
         +"correctly."+CHR(13)+CHR(13)
  DO CASE
  CASE nUpdateStat = 1 && Not existing, Cannot Create
    =MESSAGEBOX(cMsg1+;
      +"The computer system could not find this file nor could it"+CHR(13);
      +"create one. Until one exists, <YourApp> cannot be used.",0)
  CASE nUpdateStat = 2 && Not existing, Did Create
    =MESSAGEBOX(cMsg1+;
      +"The <YourApp> startup directory did not include this"+CHR(13);
      +"file so one was created for you. The new Config.fpw file"+CHR(13);
      +"contains all the required settings for the <YourApp>"+CHR(13);
      +"application to run."+CHR(13)+CHR(13);
      +"In order to activate this statement you need to RESTART the"+CHR(13);
      +"<YourApp> application.",0)
  CASE nUpdateStat = 3 && Did exist, Modified
    =MESSAGEBOX(cMsg1+;
      +"Your existing Config.fpw file has now been modified to
  contain"+CHR(13);
      +"an MVCOUNT=2000 statement. To activate this statement you
  need"+CHR(13);
      +"to RESTART the <YourApp> application.",0)
  ENDCASE


Additional query words: VFoxWin

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Keywords          : kbcode 
Technology        : kbVFPsearch kbAudDeveloper kbVFP300 kbVFP300b
Version           : 3.00 3.00b

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