Final answer:
To get the byte number of the file's current read position in C++, use the tellg() function from the ifstream class and convert the returned streampos value to a byte number by casting it to the appropriate integer type.
Step-by-step explanation:
To get the byte number of the file's current read position in C++, you can use the tellg() function from the ifstream class. The tellg() function returns a value of type streampos, which represents the current position in the stream.
You can then convert this streampos value to a byte number by casting it to the appropriate integer type.