R_CPSize() 
 Determines the original size of a compressed file
------------------------------------------------------------------------------

 Syntax
        nFileSize := R_CPSize ( cCmpFile )

 Arguments
        cCmpFile        File specification of a compressed file
                        Format  : [drive:][\path\]filename[.ext]
                        Example : C:\INVOICE\INVOICE.#BF

 Returns
        nFileSize       Original (uncompressed) size of the compressed file.
                        If an error is detected (p.e. the specified input
                        file doesn't exist) the value -1 will be returned.
                        The error can be examined using the R_LastErr ()
                        function.

 Description
        Determines what the file size of a file was before it was
        compressed by R_Compress ().
        This information can be used to check if there is enough free
        disk space before decompressing files.

 Example
        *-- Compresses the file INVOICE.DBF => INVOICE.#BF and determines
        *--     the original file size

        *-- header file of RCmpLib
        #include "RCmpLib.CH"

        LOCAL   nRetCode                        && Return code R_Compress

        nRetCode := R_Compress ( 'INVOICE.DBF', 'INVOICE.#BF' )

        IF nRetCode = CP_OKAY
                *-- Compression okay : delete the original file
                FErase ( 'INVOICE.DBF' )

                ?'The original size of INVOICE.#BF was : ', ;
                        R_CPSize ( 'INVOICE.#BF' )
        ENDIF