Basic C++ I/O

• C++ I/O is part of the standard library.
• To use it you need to include iostream
• cin is the standard input stream
• cout is the standard output stream
• Let's start with output.
  • Examples:
    • cout << "Please enter your name =>";
    • cout << endl;
    • cout << greeting << endl;
  • There are three basic components
    • The output stream (cout)
    • The stream insertion operator ( <<)
    • The end of line manipulator (endl)
  • As well as the data to be inserted into the stream.
• The output stream cout
  • is normally associated with the terminal display connected to the program (the screen)
  • This does not have to be the case, but it is the default behavior.
  • Think of it as a place to put text/data/...
• The stream insertion operator (<<)
  • Has data on the right hand side (lie)
  • And a stream on the left hand side (truth)
  • It converts the data on the right hand side to ascii and inserts it into the stream on the left hand side.
  • It then returns the stream so the operation can be repeated.
• endl
  • will send the newline character (\n) to the stream
  • Will "flush the output buffer"
• Look at the examples above.
• Standard input
  • This is more complex, we will revisit a number of times.
  • cin >> variable
    • This attempts to read ascii text from the input stream and store it in the variable.
    • It does the following:
      • skip any leading white space.
      • when non whitespace is encountered
        • Attempt to convert this to the type of the variable character by character.
        • If successful it stores the result in the variable.
        • Stop when
          • the conversion fails.
          • a whitespace is encountered.
    • This is easy with strings
      • skip all whitespace
      • store all non whitespace characters in the string
      • stop when whitespace is encountered.