Use the cfile class to read large files

With the popularization of Windows 2000 and XP, there are more and more large files, while the cfile class of MFC in vc6 only supports files not larger than 4 GB, because in the cfile class
The 32-bit integer is used to process files. The 32-bit range is the power of 2 (4 GB), and The cfile of files beyond this range cannot be managed, Microsoft. cfile class support for vc7 in. net
Files larger than 4 GB, But. NET is not popular yet, And vc6 is the preferred choice for desktop application development. Therefore, we can refer to vc7 to write a cfile inheritance class cfile64 so that it supports files larger
4 GB files:
Class cfile64: Public cfile {public: // attributesulonglong getposition (); // overridablesvirtual ulonglong seek (Longlong Loff, uint nfrom); Virtual void setlength (ulonglong dwnewlen ); ulonglong getlength (); Virtual void lockrange (ulonglong dwpos, ulonglong dwcount); Vir