Chapter 13. Input and Output

Programs must be able to write data to files or to physical output devices such as displays or printers, and to read in data from files or input devices such as a keyboard. The C standard library provides numerous functions for these purposes. This chapter presents a survey of the part of the standard library that is devoted to input and output, often referred to as the I/O library. Further details on the individual functions can be found in Part II. Apart from these library functions, the C language itself contains no input or output support at all.

All of the basic functions, macros, and types for input and output are declared in the header file stdio.h. The corresponding declarations for wide character input and output functionsthat is, for input and output of characters with the type wchar_tare contained in the header file wchar.h.