fread(3c) [sunos man page]
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 5.10 24 Jul 2002 fread(3C)
Check Out this Related Man Page
FREAD(3P) POSIX Programmer's Manual FREAD(3P) PROLOG
This manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface may differ (consult the correspond- ing Linux manual page for details of Linux behavior), or the interface may not be implemented on Linux. NAME
fread - binary input SYNOPSIS
#include <stdio.h> size_t fread(void *restrict ptr, size_t size, size_t nitems, FILE *restrict stream); DESCRIPTION
The fread() function shall read 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 shall be made to the fgetc() 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) shall be advanced by the number of bytes successfully read. If an error occurs, the resulting value of the file position indicator for the stream is unspeci- fied. If a partial element 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 shall be marked for update by the first successful execution of fgetc(), fgets(), fgetwc(), fgetws(), fread(), fscanf(), getc(), getchar(), gets(), or scanf() using stream that returns data not supplied by a prior call to ungetc() or ungetwc(). RETURN VALUE
Upon successful completion, fread() shall return 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() shall return 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 shall be set, and errno shall be set to indicate the error. ERRORS
Refer to fgetc(). The following sections are informative. EXAMPLES
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); ... APPLICATION USAGE
The ferror() or feof() functions must be used to distinguish between an error condition and an end-of-file condition. Because of possible differences in element length and byte ordering, files written using fwrite() are application-dependent, and possibly cannot be read using fread() by a different application or by the same application on a different processor. RATIONALE
None. FUTURE DIRECTIONS
None. SEE ALSO
feof(), ferror(), fgetc(), fopen(), getc(), gets(), scanf(), the Base Definitions volume of IEEE Std 1003.1-2001, <stdio.h> COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition, Standard for Information Technol- ogy -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of Electrical and Electronics Engineers, Inc and The Open Group. In the event of any discrepancy between this version and the original IEEE and The Open Group Standard, the original IEEE and The Open Group Standard is the referee document. The original Standard can be obtained online at http://www.opengroup.org/unix/online.html . IEEE
/The Open Group 2003 FREAD(3P)