将指针存储到C ++中存储在磁盘上的文件的行号

I want to store pointers to file's line numbers in an array and later I want to retrieve the specified line from disk. I can not store pointer to line number directly as when I read the file back the memory locations would have changed. So, I am storing the offset from the beginning of the file instead. For storing the offset I am using "uint_64t". However since my file size is 200GB therefore "uint_64t" is not able to represent all the offsets. I want to store pointers to file's line numbers