CP1300 C++ Files

Content

• Introduction (p.335)
  • Why have files?
  • Input and output streams
  • Devices
  • Stream ADT operations
    • Open
    • Get data from an input stream
    • Detect end of input stream
    • Put data on an output stream
  • Stream ADT is implemented by various C++ classes

• Streams (p.336)
  • Standard I/O streams are defined in iostream.h
  • File streams are defined in fstream.h. This contains the classes ofstream and ifstream.

• Output file streams (p.337)
  • Opening with Instance.open(FileName) renews the file if possible.
  • Closing with Instance.close() is good programming.
  • Using output file streams with <<
  • kbdfile.cpp - Saving integers to a file (p.339)

• Detecting errors (p.338)
  • Instance.fail() determines if the operation has failed.
  • mykbdfile.cpp - Saving integers to a file safely
  • assertkbdfile.cpp - Saving integers to a file safely using assert provides less control.

• Input file streams (p.340)
  • Opening with Instance.open(FileName) opens the file if possible.
  • Closing with Instance.close() is good programming.
  • Using output file streams with >>
  • filescr.cpp - Reading from a file (p.339)
  • Detecting end of stream with Instance.eof() is common, especially when looping through input. (p.342).

              Read first item of data
              While not end of stream do
                  Process the data
                  Read next item of data
              

  • intfile.cpp - Reading until end of stream (p.343)

• Checking if a file exists from with C++
  • fstream.h provides the ifstream (and ofstream) data type
  • CheckFile.cpp - Checking if a file exists

• Using files with functions (p.345)
  • Files must be passed by reference
  • intcopy.cpp - Copying a user specified file (p.346)
  • IntCopy.cpp (the elegant version)

• Buffered file input (p.349)
  • Reading strings with InputStreamInstance.getline(String,MaxLength) reads a whole line at once (or less if the line is too long).
  • buffcopy.cpp - Copying a user specified file line by line (p.350)

• Character input and output (p.353)
  • Single characters can be read with InputStreamInstance.get(CharacterVariable), and single characters can be output with OutputStreamInstance.put(CharacterVariable).
  • charcnt.cpp - Counting the number of characters in a file (p.354)
  • copyfile.cpp - Copying a file character by character (p.355)

• Binary files
  • Representation in text files (p.341)
  • kbdfile.cpp - Saving integers to a file (p.339)
  • Using Instance.write(&Variable,Size) and Instance.read(&Variable,Size)
  • BinaryFile.cpp - Saving integers to a file in binary format