I/O Overview

​cin&cout

• Standard in

  • Where input comes into a program by default

    • Normally the keyboard

    • Can be modified (e.g. pipes in UNIX)

• Standard out

  • Where output is sent

    • Normally the screen

    • Can be modified (e.g. pipes)

• Standard error

  • Where error messages are sent

    • Frequently set to a file

cin & cout

I/O

I/O

The Stream Model

An ostream

• turns values of various types into character sequences

• sends those characters somewhere (console, file, main memory, another computer…)

An istream

• gets characters from somewhere (console, file, main memory, another computer,…)

• turns character sequences into values of various types

The Stream Model

Supports reading and writing

• of typed entities

  • << (output) and >> (input/extraction) plus other operations

  • type-safe

  • formatted

• typically stored as text

  • but not necessarily, e.g, binary streams

• extensible

  • define your own I/O operations for your own types

• a stream can be attached to any I/O or storage device

Model