fread(3) [opendarwin man page]

FREAD(3)                                                     Linux Programmer's Manual                                                    FREAD(3)

NAME

       fread, fwrite - binary stream input/output

SYNOPSIS

       #include <stdio.h>

       size_t fread(void *ptr, size_t size, size_t nmemb, FILE *stream);

       size_t fwrite(const void *ptr, size_t size, size_t nmemb,
                     FILE *stream);

DESCRIPTION

       The  function  fread()  reads nmemb items of data, each size bytes long, from the stream pointed to by stream, storing them at the location
       given by ptr.

       The function fwrite() writes nmemb items of data, each size bytes long, to the stream pointed to by stream, obtaining them from  the  loca-
       tion given by ptr.

       For nonlocking counterparts, see unlocked_stdio(3).

RETURN VALUE

       On  success, fread() and fwrite() return the number of items read or written.  This number equals the number of bytes transferred only when
       size is 1.  If an error occurs, or the end of the file is reached, the return value is a short item count (or zero).

       fread() does not distinguish between end-of-file and error, and callers must use feof(3) and ferror(3) to determine which occurred.

ATTRIBUTES

       For an explanation of the terms used in this section, see attributes(7).

       +------------------+---------------+---------+
       |Interface         | Attribute     | Value   |
       +------------------+---------------+---------+
       |fread(), fwrite() | Thread safety | MT-Safe |
       +------------------+---------------+---------+
CONFORMING TO

       POSIX.1-2001, POSIX.1-2008, C89.

SEE ALSO

       read(2), write(2), feof(3), ferror(3), unlocked_stdio(3)

COLOPHON

       This page is part of release 4.15 of the Linux man-pages project.  A description of the project, information about reporting bugs, and  the
       latest version of this page, can be found at https://www.kernel.org/doc/man-pages/.

GNU                                                                 2015-07-23                                                            FREAD(3)

fread(3C)						   Standard C Library Functions 						 fread(3C)

NAME

       fread - binary input

SYNOPSIS

       #include <stdio.h>

       size_t fread(void *ptr, size_t size, size_t nitems, FILE *stream);

DESCRIPTION

       The fread() function reads into the array pointed to by ptr up to nitems elements whose size is specified by size in bytes, from the stream
       pointed to by stream. For each object, size calls are made to the fgetc(3C) function and the results stored, in the order read, in an array
       of  unsigned char exactly overlaying the object. The file-position indicator for the stream (if defined) is advanced by the number of bytes
       successfully read. If an error occurs, the resulting value of the file-position indicator for the stream is unspecified. If a partial  ele-
       ment is read, its value is unspecified.

       The  fread()  function  may  mark  the  st_atime field of the file associated with stream for update. The st_atime field will be marked for
       update by the first successful execution of fgetc(3C), fgets(3C),  fgetwc(3C),  fgetws(3C),  fread(),  fscanf(3C),  getc(3C),  getchar(3C),
       gets(3C), or scanf(3C) using stream that returns data not supplied by a prior call to ungetc(3C) or ungetwc(3C).

RETURN VALUES

       Upon  successful  completion,  fread()  returns the number of elements successfully read, which is less than nitems only if a read error or
       end-of-file is encountered. If size or nitems is 0, fread() returns 0 and the contents of the array and the  state  of  the  stream  remain
       unchanged.  Otherwise, if a read error occurs, the error indicator for the stream is set and errno is set to indicate the error.

ERRORS

       Refer to fgetc(3C).

EXAMPLES

       Example 1 Reading from a Stream

       The following example reads a single element from the fp stream into the array pointed to by buf.

	 #include <stdio.h>
	 ...
	 size_t bytes_read;
	 char buf[100];
	 FILE *fp;
	 ...
	 bytes_read = fread(buf, sizeof(buf), 1, fp);
	 ...

USAGE

       The ferror() or feof() functions must be used to distinguish between an error condition and end-of-file condition. See ferror(3C).

       Because of possible differences in element length and byte ordering, files written using fwrite(3C) are application-dependent, and possibly
       cannot be read using fread() by a different application or by the same application on a different processor.

ATTRIBUTES

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Interface Stability	     |Standard			   |
       +-----------------------------+-----------------------------+
       |MT-Level		     |MT-Safe			   |
       +-----------------------------+-----------------------------+

SEE ALSO

       read(2), fclose(3C), ferror(3C), fopen(3C), getc(3C), gets(3C), printf(3C), putc(3C), puts(3C), attributes(5), standards(5)

SunOS 5.11							    24 Jul 2002 							 fread(3C)