setbuf(3S) — sys5



SETBUF(3S)      DOMAIN/IX Reference Manual (SYS5)      SETBUF(3S)



NAME
     setbuf, setvbuf - assign buffering to a stream

USAGE
     #include <stdio.h>

     void setbuf (stream, buf)
     FILE *stream;
     char *buf;

     int setvbuf (stream, buf, type, size)
     FILE *stream;
     char *buf;
     int type, size;

DESCRIPTION
     Setbuf may be used after a stream has been opened, but
     before it is read or written.  It causes the specified
     stream to buffer input or output in buf rather than in an
     automatically allocated buffer.  If buf is the NULL pointer,
     input and output will be completely unbuffered.

     A constant BUFSIZ, defined in the <stdio.h> header file,
     tells how big an array is needed:

          char buf[BUFSIZ];
     Setvbuf may be used after a stream has been opened but
     before it is read or written.  Type determines how stream
     will be buffered.  Legal values for type (defined in
     stdio.h) are:

         _IOFBF
             causes input and output to be fully buffered.

         _IOLBF
             causes output to be line buffered; the buffer will
             be flushed when a newline is written, the buffer is
             full, or input is requested.

         _IONBF
             causes input and output to be completely unbuffered.
             If buf is not the NULL pointer, the array it points
             to will be used for buffering, instead of an
             automatically allocated buffer.  Size specifies the
             size of the buffer to be used.  The constant BUFSIZ
             in <stdio.h> is suggested as a good buffer size.  If
             input and output is unbuffered, buf and size are
             ignored.  By default, output to a terminal is line
             buffered and all other input and output is fully
             buffered.





Printed 5/10/85                                          SETBUF-1



SETBUF(3S)      DOMAIN/IX Reference Manual (SYS5)      SETBUF(3S)



NOTES
     A common source of error is allocating buffer space as an
     ``automatic'' variable in a code block, and then failing to
     close the stream in the same block.

DIAGNOSTICS
     If an illegal value for type or size is provided, setvbuf
     returns a non-zero value. Otherwise, it returns zero.

RELATED INFORMATION
     fopen(3S), getc(3S), malloc(3C), putc(3S), stdio(3S)












































SETBUF-2                                          Printed 5/10/85

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