Binary data files need a special program to read and write. Because binary data files contain only 0 and 1. 

The ifstream class is used to create an object for opening a file to read.  

The member function get() is used to get a single character from a file. And put() is used to write a character to a file. 

The steps to process a file in C++  are

1. Open the file
2. Read or write the file
3. Close the file

The current position of the file pointer is given by the tellp() and tellg() member functions of ostream and istream respectively. 

The open mode in, out and ate are the valid modes for reading, writing and appending respectively. There is no any ale mode in C++. 

The open mode “ate” is used to open the file by position the file pointer at the end of file. 

The function seekg() is used to position the file pointer at a specific place. So, the statement filepointer.seekg(0L,ios::beg); positions the file pointer at the beginning of the file. 

The file opening mode ios::nocreate gives the error if the file does not already exist. 

The istrstream class is used to create an object for accessing the streams of bytes from memory.

The correct format to check whether a file stream f1 was successfully opened or not is as follows: if(f1.is_open()) { .................. } 

The member function good() is used to check whether the state of the stream for input/output operation is good or not. 

The get(ch), getline() and extraction operators can be used to read a text file. But open() function can be used only to open the file in a particular mode.

The default mode for a open() member function of fstream class is ios::in | ios::out. 

To display the integer variable in octal format, we have to use the “oct” keyword between the cout and variable using << operator.