Using Win32 functions in Visual FoxPro Image Gallery
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How to generate GUID values

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Before you begin:
The result is returned in a format like that of the following sample:
{557cf400-1a04-11d3-9a73-0000f81ef32e}

See also:
  • Generating random UUID values
  • Generating sequential UUID values

  • DO declare
    
    LOCAL cGUID, cGUIDString, cGUID1
    cGUID = REPLICATE(CHR(0), 16)  && 128 bits
    
    IF CoCreateGuid(@cGUID) = 0
        cGUIDString = StringFromGUID(cGUID)
        ? cGUID
        ? cGUIDString
    
        * converting from String back to GUID
        cGUID1 = REPLICATE(CHR(0), 16)
        = CLSIDFromString(STRCONV(cGUIDString,5), @cGUID1)
        ? cGUID1
    ENDIF
    * end of main
    
    FUNCTION StringFromGUID(cGUID)
        LOCAL cBuffer, nBufsize
        nBufsize=128
        cBuffer = REPLICATE(CHR(0), nBufsize*2)
        = StringFromGUID2(cGUID, @cBuffer, nBufsize)
        cBuffer = SUBSTR(cBuffer, 1, AT(CHR(0)+CHR(0), cBuffer))
    RETURN STRCONV(cBuffer, 6)
    
    PROCEDURE declare
        DECLARE INTEGER CoCreateGuid IN ole32 STRING @pguid
    
        DECLARE INTEGER CLSIDFromString IN ole32;
            STRING lpsz, STRING @pclsid
    
        DECLARE INTEGER StringFromGUID2 IN ole32;
            STRING rguid, STRING @lpsz, INTEGER cchMax
    
    

    User rating: 9/10 (1 votes)
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    844 bytes  
    Created: 2004-07-15 13:24:36  
    Modified: 2013-10-01 12:23:16  
    Visits in 7 days: 46  
    Listed functions:
    CLSIDFromString
    CoCreateGuid
    StringFromGUID2
    Printer friendly API declarations
    My comment:
    The GUID is a unique 128-bit integer used for CLSIDs and interface identifiers.

    See also Microsoft Knowledge Base Article 269387 How To Obtain a GUID in Visual FoxPro

    * * *
    Having a connection to SQL Server, Guids can be generated with the NewId() function.
    FUNCTION NewGuid() As String
            IF SQLEXEC(1, "SELECT NewId() As guid", "csGuid") > 0
                    RETURN csGuid.guid
            ELSE
                    RETURN NULL
            ENDIF

    Another way is using the Scriptlet.TypeLib COM. Note that you must create a new instance of the class for each Guid to be generated, which probably produces some overhead.
    obj = CreateObject("Scriptlet.TypeLib")
    ? SUBSTR(obj.GUID,2,36)

    After a simple test I can estimate that the COM procedure is 5 to 10% faster than the SQL one (local server); and API is the winner creating GUID 15-20 times faster than COM -- for example, 0.24 seconds versus 4 seconds per 10,000 guids created.

    On the same computer C# code generated 1,000,000 guids in 1.05 seconds.
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    User Contributed Notes:
    A.M. | 2006-07-19 15:38:05
    DECLARE INTEGER UuidCreate IN rpcrt4 STRING @UUID

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