setbuf(3)                           CLIX                           setbuf(3)



  NAME

    setbuf, setvbuf - Assigns buffering to a stream

  LIBRARY

    Standard C Library (libc.a)

  SYNOPSIS

    #include <stdio.h>

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

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

  PARAMETERS

    stream   A stream

    buf      A buffer into which to store input data

    type     An integer that specifies how input is buffered

    size     The size of the buffer to be used

  DESCRIPTION

    The setbuf() function may be used after a stream has been opened but
    before it is read or written.  It causes the array pointed to by buf to be
    used instead of an automatically allocated buffer.  If buf is the pointer
    input/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];

    The setvbuf() function may be used after a stream has been opened but
    before it is read or written.  The type parameter determines how stream
    will be buffered.  Legal values for type (defined in stdio.h) are:

    _IOFBF   Causes input/output to be fully buffered.

    _IOLBF   Causes output to be line buffered; the buffer will be flushed



  2/94 - Intergraph Corporation                                              1

  setbuf(3)                           CLIX                           setbuf(3)



             when a newline is written, the buffer is full, or input is
             requested.

    IONBF    Causes input/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.  The size
    parameter specifies the size of the buffer to be used.  The constant
    BUFSIZ in <stdio.h> is suggested as a good buffer size.  If input/output
    is unbuffered, buf and size are ignored.

    By default, output to a terminal is line buffered and all other
    input/output is fully buffered.

  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.

  RETURN VALUES

    If an illegal value for type or size is provided, setvbuf returns a
    nonzero value.  Otherwise, the value returned will be zero.

  RELATED INFORMATION

    Functions: fopen(3), getc(3), malloc(3), putc(3), stdio(3)


























  2                                              Intergraph Corporation - 2/94