HOWTO: Generate Random Strings

ID: Q192353

The information in this article applies to:

Microsoft Visual FoxPro for Windows, versions 3.0, 3.0b, 5.0, 5.0a, 6.0
Microsoft FoxPro for UNIX, version 2.6
Microsoft FoxPro for MS-DOS, versions 2.6, 2.6a
Microsoft FoxPro for Windows, versions 2.6, 2.6a
Microsoft Visual FoxPro for Macintosh, version 3.0b
Microsoft FoxPro for Macintosh, version 2.6a

SUMMARY

When testing SQL functions or creating test data, it is useful to be able to generate random string data. The FoxPro function SYS(2015) creates ten character random strings for use as procedure names. However, SYS(2015) does not allow the developer to specify a range of ASCII characters to use, nor does it allow the developer to specify the length of the string. This article demonstrates how to create and use the RandomString() function.

MORE INFORMATION

Save the following code to a program file and run it. The WAIT WINDOW command displays a new random string each time a key is pressed. Press the ESC key to end the program.


   *-- Code begins here.
   SET TALK OFF
   ON ESCAPE CANCEL
   DO WHILE .T.  && Press the escape key to quit
       WAIT WINDOW RandomString(65,122,1,15)
   ENDDO
   SET TALK ON

   *----------------------------------------------------------
   *-- Function:   RandomString()
   *-- Summary:    Generates a string of random characters
   *-- Usage:      RandomString(nLboundAscii, nUboundAscii,
   *--               nLBoundLength, nUBoundLength)
   *-- Parameters: nLBoundAscii - Lowest ASCII value to use.
   *--             nUBoundAscii - Highest ASCII value to use.
   *--             nLBoundLength - Shortest string to generate.
   *--             nUBoundLength - Longest string to generate.
   *-- Example:    lsReturn = RandomString(65,122,1,15)
   *----------------------------------------------------------
   FUNCTION RandomString
   PARAMETERS liLowerBAscii, liUpperBAscii, ;
     liLowerBLength, liUpperBLength

   *-- Initialize variables.
   lsString = ""
   liLength = 0
   liCounter = 0

   *-- Check for valid parameters and correct if needed.
   IF liLowerBAscii < 0
      liLowerBAscii = 0
   ENDIF
   IF liLowerBAscii > 255
      liLowerBAscii = 255
   ENDIF
   IF liUpperBAscii < 0
      liUpperBAscii = 0
   ENDIF
   IF liUpperBAscii > 255
      liUpperBAscii = 255
   ENDIF
   IF liLowerBLength < 0
      liLowerBLength = 0
   ENDIF
   liLength = INT((liUpperBLength - liLowerBLength + 1) ;
     * RAND(-1) + liLowerBLength)

   FOR liCounter = 1 TO liLength
      lsString = lsString + CHR(INT((;
          liUpperBAscii - liLowerBAscii + 1) ;
        * RAND() + liLowerBAscii))
   ENDFOR
   RETURN lsString
   *-- Code ends here.

REFERENCES

Additional query words: kbVFp300b kbVFp300 kbVFp500 kbVFp500a kbVFp600 kbXBase kbunix kbmac

Keywords :
Version : MACINTOSH:2.6a,3.0b; MS-DOS:2.6,2.6a; UNIX:2.6; WINDOWS:2.6,2.6a,3.0,3.0b,5.0,5.0a,6.0
Platform : MACINTOSH MS-DOS UNIX WINDOWS
Issue type : kbhowto