I the heir of all the ages, in the foremost files of time.
A file is a collection of related data. C treats a file as a series of bytes. Many files reside on disk; however, devices like terminals, printers, and magnetic tapes are also considered files.
The C library contains a large number of routines for manipulating
files. The declarations for the structures and functions used by the
file functions are stored in the standard include file
<stdio.h>. Before doing anything with
files, you must put the line:
at the beginning of your program.
The declaration for a file variable is:
#include <stdio.h> FILE *in_file; /* file containing the input data */
Before a file can be used, it must be opened using the
fopen returns a pointer to the file structure
for the file. The format for
is a file variable. A value of
NULL is returned on error.
is the actual name of the file (data.txt, temp.dat, etc.).
indicates if the file is to be read or written. mode is
"w" for writing and
"r" for reading. The flag “b” can be
added to indicate a binary file. Omitting the binary flag
indicates an ASCII (text) file. (See Section 14.2 for a description
of ASCII and binary files.)
Flags can be combined. So “wb” is used to write a binary file.
The function returns a file handle that will be used in subsequent I/O operations. ...