1fread(3C)                Standard C Library Functions                fread(3C)
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NAME

6       fread - binary input
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SYNOPSIS

9       #include <stdio.h>
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11       size_t fread(void *ptr, size_t size, size_t nitems, FILE *stream);
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DESCRIPTION

15       The  fread()  function  reads  into  the  array pointed to by ptr up to
16       nitems elements whose size is specified by  size  in  bytes,  from  the
17       stream  pointed  to  by stream. For each object, size calls are made to
18       the fgetc(3C) function and the results stored, in the order read, in an
19       array of unsigned char exactly overlaying the object. The file-position
20       indicator for the stream (if defined) is  advanced  by  the  number  of
21       bytes successfully read. If an error occurs, the resulting value of the
22       file-position indicator for the stream is  unspecified.  If  a  partial
23       element is read, its value is unspecified.
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26       The fread() function may mark the st_atime field of the file associated
27       with stream for update. The st_atime field will be marked for update by
28       the  first  successful  execution  of fgetc(3C), fgets(3C), fgetwc(3C),
29       fgetws(3C), fread(), fscanf(3C), getc(3C),  getchar(3C),  gets(3C),  or
30       scanf(3C)  using  stream that returns data not supplied by a prior call
31       to ungetc(3C) or ungetwc(3C).
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RETURN VALUES

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

42       Refer to fgetc(3C).
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EXAMPLES

45       Example 1 Reading from a Stream
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48       The  following  example  reads a single element from the fp stream into
49       the array pointed to by buf.
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52         #include <stdio.h>
53         ...
54         size_t bytes_read;
55         char buf[100];
56         FILE *fp;
57         ...
58         bytes_read = fread(buf, sizeof(buf), 1, fp);
59         ...
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USAGE

63       The ferror() or feof() functions must be used to distinguish between an
64       error condition and end-of-file condition. See ferror(3C).
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67       Because  of  possible  differences in element length and byte ordering,
68       files written using fwrite(3C) are application-dependent, and  possibly
69       cannot  be read using fread() by a different application or by the same
70       application on a different processor.
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ATTRIBUTES

73       See attributes(5) for descriptions of the following attributes:
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78       ┌─────────────────────────────┬─────────────────────────────┐
79       │      ATTRIBUTE TYPE         │      ATTRIBUTE VALUE        │
80       ├─────────────────────────────┼─────────────────────────────┤
81       │Interface Stability          │Standard                     │
82       ├─────────────────────────────┼─────────────────────────────┤
83       │MT-Level                     │MT-Safe                      │
84       └─────────────────────────────┴─────────────────────────────┘
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SEE ALSO

87       read(2),  fclose(3C),  ferror(3C),   fopen(3C),   getc(3C),   gets(3C),
88       printf(3C), putc(3C), puts(3C), attributes(5), standards(5)
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92SunOS 5.11                        24 Jul 2002                        fread(3C)
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