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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
       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 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),  getdelim(3C),
       getline(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 suc‐
       cessfully  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(7) for descriptions of the following attributes:


       tab() box; cw(2.75i) |cw(2.75i) lw(2.75i) |lw(2.75i) ATTRIBUTE  TYPEAT‐
       TRIBUTE  VALUE _ Interface StabilityCommitted _ MT-LevelMT-Safe _ Stan‐
       dardSee standards(7).


SEE ALSO
       read(2), fclose(3C),  ferror(3C),  fopen(3C),  getc(3C),  getdelim(3C),
       getline(3C),  gets(3C),  printf(3C), putc(3C), puts(3C), attributes(7),
       standards(7)



Oracle Solaris 11.4               24 Jul 2002                        fread(3C)
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