stdio.html

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and returns zero if successful.
If the file is open when you remove it,
the result is implementation defined. After you remove it, you
cannot open it as an existing file.</P>

<H2><A NAME="rename"><CODE>rename</CODE></A></H2>

<PRE>int <B>rename</B>(const char *old, const char *new);</PRE>

<P>The function renames the file with the filename <CODE>old</CODE> to
have the filename <CODE>new</CODE> and returns zero if successful. If a
file with the filename <CODE>new</CODE> already exists,
the result is implementation defined.
After you rename it, you cannot open the file
with the filename <CODE>old</CODE>.</P>

<H2><A NAME="rewind"><CODE>rewind</CODE></A></H2>

<PRE>void <B>rewind</B>(FILE *stream);</PRE>

<P>The function calls
<CODE><A HREF="#fseek">fseek</A>(stream, 0L, SEEK_SET)</CODE>
and then clears the error indicator for the stream <CODE>stream</CODE>.</P>

<H2><A NAME="scanf"><CODE>scanf</CODE></A></H2>

<PRE>int <B>scanf</B>(const char *format, ...);</PRE>

<P>The function
<A HREF="lib_scan.html#Scan Functions">scans formatted text</A>,
under the control of the format <CODE>format</CODE>
and any additional arguments. It obtains each
scanned character from the stream
<A HREF="#stdin"><CODE>stdin</CODE></A>. It returns the number
of input items matched and assigned, or it returns
<A HREF="#EOF"><CODE>EOF</CODE></A> if the
function does not store values before it sets the end-of-file or error
indicators for the stream.</P>

<H2><A NAME="SEEK_CUR"><CODE>SEEK_CUR</CODE></A></H2>

<PRE>#define <B>SEEK_CUR</B> <I>&lt;integer constant expression&gt;</I></PRE>

<P>The macro yields the value of the <CODE>mode</CODE> argument to
<A HREF="#fseek"><CODE>fseek</CODE></A>
to indicate seeking relative to the current
file-position indicator.</P>

<H2><A NAME="SEEK_END"><CODE>SEEK_END</CODE></A></H2>

<PRE>#define <B>SEEK_END</B> <I>&lt;integer constant expression&gt;</I></PRE>

<P>The macro yields the value of the <CODE>mode</CODE> argument to
<A HREF="#fseek"><CODE>fseek</CODE></A>
to indicate seeking relative to the end of the file.</P>

<H2><A NAME="SEEK_SET"><CODE>SEEK_SET</CODE></A></H2>

<PRE>#define <B>SEEK_SET</B> <I>&lt;integer constant expression&gt;</I></PRE>

<P>The macro yields the value of the <CODE>mode</CODE> argument to
<A HREF="#fseek"><CODE>fseek</CODE></A>
to indicate seeking relative to the beginning of the file.</P>

<H2><A NAME="setbuf"><CODE>setbuf</CODE></A></H2>

<PRE>void <B>setbuf</B>(FILE *stream, char *buf);</PRE>

<P>If <CODE>buf</CODE> is not a null pointer, the function calls
<CODE><A HREF="#setvbuf">setvbuf</A>(stream, buf,
__IOFBF, BUFSIZ)</CODE>,
specifying full buffering with
<A HREF="#_IOFBF"><CODE>_IOFBF</CODE></A>
and a buffer size of
<A HREF="#BUFSIZ"><CODE>BUFSIZ</CODE></A> characters.
Otherwise, the function calls
<CODE><A HREF="#setvbuf">setvbuf</A>(stream,
0, _IONBF, BUFSIZ)</CODE>,
specifying no buffering with
<A HREF="#_IONBF"><CODE>_IONBF</CODE></A>.</P>

<H2><A NAME="setvbuf"><CODE>setvbuf</CODE></A></H2>

<PRE>int <B>setvbuf</B>(FILE *stream, char *buf, int mode,
    size_t size);</PRE>

<P>The function sets the buffering mode for the stream <CODE>stream</CODE>
according to <CODE>buf</CODE>, <CODE>mode</CODE>, and <CODE>size</CODE>.
It returns zero if successful.
If <CODE>buf</CODE> is not a null pointer, then <CODE>buf</CODE>
is the address of the first element of an array of <I>char</I> of
size <CODE>size</CODE> that can be used as the stream buffer. Otherwise,
<CODE>setvbuf</CODE> can allocate a stream buffer that is freed when the
file is closed. For <CODE>mode</CODE> you must supply one of the following
values:</P>

<UL>
<LI><B><A HREF="#_IOFBF"><CODE>_IOFBF</CODE></A></B>
-- to indicate full buffering

<LI><B><A HREF="#_IOLBF"><CODE>_IOLBF</CODE></A></B>
-- to indicate line buffering

<LI><B><A HREF="#_IONBF"><CODE>_IONBF</CODE></A></B>
-- to indicate no buffering
</UL>

<P>You must call <CODE>setvbuf</CODE> after you call
<A HREF="#fopen"><CODE>fopen</CODE></A>
to associate a file with that stream and before you call a library
function that performs any other operation on the stream.</P>

<H2><A NAME="size_t"><CODE>size_t</CODE></A></H2>

<PRE>typedef <I>ui-type</I> <B>size_t</B>;</PRE>

<P>The type is the unsigned integer type <CODE><I>ui-type</I></CODE>
of an object that you declare to store the result of the
<A HREF="express.html#sizeof operator"><I>sizeof</I></A> operator.</P>

<H2><A NAME="sprintf"><CODE>sprintf</CODE></A></H2>

<PRE>int <B>sprintf</B>(char *s, const char *format, ...);</PRE>

<P>The function
<A HREF="lib_prin.html#Print Functions">generates formatted text</A>,
under the control of the format <CODE>format</CODE>
and any additional arguments, and stores
each generated character in successive locations of the array object whose
first element has the address <CODE>s</CODE>. The function concludes by
storing a null character in the next location of the array. It returns
the number of characters generated -- not including the null character.

<H2><A NAME="sscanf"><CODE>sscanf</CODE></A></H2>

<PRE>int <B>sscanf</B>(const char *s, const char *format, ...);</PRE>

<P>The function
<A HREF="lib_scan.html#Scan Functions">scans formatted text</A>,
under the control of the format <CODE>format</CODE>
and any additional arguments. It accesses each scanned
character from successive locations of the array object whose first
element has the address <CODE>s</CODE>.
It returns the number of items matched
and assigned, or it returns
<A HREF="#EOF"><CODE>EOF</CODE></A>
if the function does not store
values before it accesses a null character from the array.</P>

<H2><A NAME="stderr"><CODE>stderr</CODE></A></H2>

<PRE>#define <B>stderr</B> <I>&lt;pointer to FILE rvalue&gt;</I></PRE>

<P>The macro yields a pointer to the object that controls the standard
error output stream.</P>

<H2><A NAME="stdin"><CODE>stdin</CODE></A></H2>

<PRE>#define <B>stdin</B> <I>&lt;pointer to FILE rvalue&gt;</I></PRE>

<P>The macro yields a pointer to the object that controls the standard
input stream.</P>

<H2><A NAME="stdout"><CODE>stdout</CODE></A></H2>

<PRE>#define <B>stdout</B> <I>&lt;pointer to FILE rvalue&gt;</I></PRE>

<P>The macro yields a pointer to the object that controls the standard
output stream.</P>

<H2><A NAME="tmpfile"><CODE>tmpfile</CODE></A></H2>

<PRE>FILE *<B>tmpfile</B>(void)</PRE>

<P>The function creates a temporary binary file with the filename
<CODE><I>temp-name</I></CODE> and then has the same effect as calling
<CODE><A HREF="#fopen">fopen</A>(<I>temp-name</I>,
"wb+")</CODE>.
The file <CODE><I>temp-name</I></CODE> is removed when the program closes
it, either by calling
<A HREF="#fclose"><CODE>fclose</CODE></A>
explicitly or at normal program termination.
The filename <CODE><I>temp-name</I></CODE> does not conflict with
any filenames that you create. If the open is successful, the function
returns a pointer to the object controlling the stream; otherwise,
it returns a null pointer.</P>

<H2><A NAME="TMP_MAX"><CODE>TMP_MAX</CODE></A></H2>

<PRE>#define <B>TMP_MAX</B> <I>&lt;integer constant expression &gt;= 25&gt;</I></PRE>

<P>The macro yields the minimum number of distinct filenames created
by the function
<A HREF="#tmpnam"><CODE>tmpnam</CODE></A>.</P>

<H2><A NAME="tmpnam"><CODE>tmpnam</CODE></A></H2>

<PRE>char *<B>tmpnam</B>(char *s);</PRE>

<P>The function creates a unique filename <CODE><I>temp-name</I></CODE> and
returns a pointer to the filename. If <CODE>s</CODE> is not a null pointer,
then <CODE>s</CODE> must be the address
of the first element of an array at least of size
<A HREF="#L_tmpnam"><CODE>L_tmpnam</CODE></A>.
The function stores <CODE><I>temp-name</I></CODE>
in the array and returns <CODE>s</CODE>.
Otherwise, if <CODE>s</CODE> is a null
pointer, the function stores <CODE><I>temp-name</I></CODE>
in a static-duration array and returns the address of its first element.
Subsequent calls to <CODE>tmpnam</CODE>
can alter the values stored in this array.</P>

<P>The function returns unique filenames for each of the first
<A HREF="#TMP_MAX"><CODE>TMP_MAX</CODE></A>
times it is called, after which its behavior is implementation defined.
The filename <CODE><I>temp-name</I></CODE>
does not conflict with any filenames that you create.</P>

<H2><A NAME="ungetc"><CODE>ungetc</CODE></A></H2>

<PRE>int <B>ungetc</B>(int c, FILE *stream);</PRE>

<P>If <CODE>c</CODE> is not equal to
<A HREF="#EOF"><CODE>EOF</CODE></A>, the function stores
<CODE>(unsigned char)c</CODE> in the object
whose address is <CODE>stream</CODE>
and clears the end-of-file indicator. If <CODE>c</CODE> equals
<A HREF="#EOF"><CODE>EOF</CODE></A>
or the store cannot occur, the function returns
<A HREF="#EOF"><CODE>EOF</CODE></A>; otherwise,
it returns <CODE>(unsigned char)c</CODE>. A subsequent library function
call that reads a character from the stream <CODE>stream</CODE> obtains
this stored value, which is then forgotten.</P>

<P>Thus, you can effectively
<B><A NAME="push back">push back</A></B> a character to a
stream after reading a character. (You need not push back the same
character that you read.) An implementation can let you push back
additional characters before you read the first one. You read the
characters in reverse order of pushing them back to the stream. You
cannot portably:</P>

<UL>
<LI>push back more than one character

<LI>push back a character if the file-position indicator is at the
beginning of the file

<LI>Call
<A HREF="#ftell"><CODE>ftell</CODE></A>
for a text file that has a character currently pushed back
</UL>

<P>A call to the functions
<A HREF="#fseek"><CODE>fseek</CODE></A>,
<A HREF="#fsetpos"><CODE>fsetpos</CODE></A>, or
<A HREF="#rewind"><CODE>rewind</CODE></A>
for the stream causes the stream to forget any pushed-back characters.
For a binary stream, the file-position indicator is decremented for
each character that is pushed back.</P>

<H2><A NAME="vfprintf"><CODE>vfprintf</CODE></A></H2>

<PRE>int <B>vfprintf</B>(FILE *stream, const char *format,
     va_list ap);</PRE>

<P>The function
<A HREF="lib_prin.html#Print Functions">generates formatted text</A>,
under the control of the format <CODE>format</CODE>
and any additional arguments, and writes
each generated character to the stream <CODE>stream</CODE>.
It returns the number
of characters generated, or it returns a negative value if the function
sets the error indicator for the stream.</P>

<P>The function accesses additional arguments by using the context
information designated by <CODE>ap</CODE>.
The program must execute the macro
<A HREF="stdarg.html#va_start"><CODE>va_start</CODE></A>
before it calls the function, and then execute the macro
<A HREF="stdarg.html#va_end"><CODE>va_end</CODE></A>
after the function returns.</P>

<H2><A NAME="vprintf"><CODE>vprintf</CODE></A></H2>

<PRE>int <B>vprintf</B>(const char *format,
    va_list ap);</PRE>

<P>The function
<A HREF="lib_prin.html#Print Functions">generates formatted text</A>,
under the control of the format <CODE>format</CODE>
and any additional arguments, and writes
each generated character to the stream
<A HREF="#stdout"><CODE>stdout</CODE></A>.
It returns the number of characters generated,
or a negative value if the function sets
the error indicator for the stream.</P>

<P>The function accesses additional arguments by using the context
information designated by <CODE>ap</CODE>.
The program must execute the macro
<A HREF="stdarg.html#va_start"><CODE>va_start</CODE></A>
before it calls the function, and then execute the macro
<A HREF="stdarg.html#va_end"><CODE>va_end</CODE></A>
after the function returns.</P>

<H2><A NAME="vsprintf"><CODE>vsprintf</CODE></A></H2>

<PRE>int <B>vsprintf</B>(char *s, const char *format,
    va_list ap);</PRE>

<P>The function
<A HREF="lib_prin.html#Print Functions">generates formatted text</A>,
under the control of the format <CODE>format</CODE>
and any additional arguments, and stores
each generated character in successive locations of the array object whose
first element has the address <CODE>s</CODE>. The function concludes by
storing a null character in the next location of the array. It returns
the number of characters generated -- not including the null character.</P>

<P>The function accesses additional arguments by using the context
information designated by <CODE>ap</CODE>.
The program must execute the macro
<A HREF="stdarg.html#va_start"><CODE>va_start</CODE></A>
before it calls the function, and then execute the macro
<A HREF="stdarg.html#va_end"><CODE>va_end</CODE></A>
after the function returns.</P>

<HR>
<P>See also the
<B><A HREF="index.html#Table of Contents">Table of Contents</A></B> and the
<B><A HREF="_index.html">Index</A></B>.</P>

<P><I>
<A HREF="crit_pb.html">Copyright</A> &#169; 1989-2002
by P.J. Plauger and Jim Brodie. All rights reserved.</I></P>

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