Chapter 14 Reading Assignment

Chapter 14 describes advanced concepts surrounding C++ files.

Section 14.1 - Files

What is the difference between the fstream, ifstream, and ostream classes?

List two different ways to open a file.

How do you open a file for both input and output?

What is a possible disadvantage of using the eof() member function to detect end-of-file, rather than the fail() member function?

Section 14.2 - Output formatting

An I/O manipulator can be used to alter the formatting of output data sent to an stream. Briefly define each of these:

• setw( int)
• showpoint
• left, right
• fixed
• setprecision( int)

The I/O manipulators are also available as member functions to a stream. Show how each of the manipulators above can be invoked using a function call.

The setw() modifier has a fundamental difference in it behavior than the other modifiers. What is it?

What is a strstream?

Section 14.3 - Passing file stream objects to functions

Is it better to pass stream objects "pass-by-value" or "pass-by-reference"? Why?

Section 14.4 - More detailed error testing

The fail() member function can detect the failure of a stream. How can the stream be returned to normal function after an error.

Section 14.5 - Member functions

Describe each fstream member function:

• getline( char *, int, char) ; 
• get( char &) ; 
• put( char) ; 
• seekg( long, offset) ;

Use seekg() to accomplish the following on an fstream:

• Rewind the fstream to the beginning
• Set the "get pointer" to the end of the fstream
• Set the "get pointer" to 12 bytes past its current location
• Set the "get pointer" to 100 bytes before the end of the fstream

Section 14.6 - Working with multiple files

If you need 12 files opened in your program at one time, how can this be accomplished in C++?

Section 14.7 - Binary files

Why are binary files smaller than ASCII files? Why are they faster?

What does the ios::binary flag do? This is a trick question... if you can tell me, I'd like to know.

Here are the binary I/O member functions:

• read( char *, int) ; 
• write( char *, int) ; 

Show an example of reading 20 bytes from an fstream. Show an example of writing 100 bytes.

Section 14.8 - Structure Blasters

Note: The archaic term for this section is "Structure Blasters" because structures in C were "blasted" to/from files in a single function call.

Why must structures contain only fixed-length fields to be read/written using C++ binary read/write functions? What is an example of a field that is not fixed-length and cannot be "blasted".

Can structures that contain pointers to other structures be "blasted"?

Show an example of reading a structure called Example from an fstream. Show an example writing a structure called DormRoom to an fstream.

Section 14.9 - Random-access files

What is the difference between seekg and seekp?

Why is this section called "random-access files"? What new capability does it describe?

What do these guys do:

• long tellg() ; 
• long tellp() ; 

Section 14.10 - Opening a file for both input and output

Done.

If you're still a little foggy, the "Review Questions and Exercises" fill-in-the-blanks section is pretty nice.