ios.html

ST20 Embedded Toolset R2.0.5用于开发基于ST20芯片机顶盒软件的开发平台,2.0.5版本,国内找不到的.在国外论坛上花了N天才找到!

    streamsize <B><A HREF="#ios_base::width">width</A></B>() const;
    stramsize <B><A HREF="#ios_base::width">width</A></B>(streamsize newwidth);
    locale <B><A HREF="#ios_base::imbue">imbue</A></B>(const locale&amp; loc);
    locale <B><A HREF="#ios_base::getloc">getloc</A></B>() const;
    static int <B><A HREF="#ios_base::xalloc">xalloc</A></B>();
    long&amp; <B><A HREF="#ios_base::iword">iword</A></B>(int idx);
    void *&amp; <B><A HREF="#ios_base::pword">pword</A></B>(int idx);
    typedef void *(<B><A HREF="#ios_base::event_callback">event_callback</A></B>(event ev,
        ios_base&amp; iosbase, int idx);
    void <B><A HREF="#ios_base::register_callback">register_callback</A></B>(event_callback pfn, int idx);
    static bool <B><A HREF="#ios_base::sync_with_stdio">sync_with_stdio</A></B>(bool newsync = true);
protected:
    <B><A HREF="#ios_base::ios_base">ios_base</A></B>();
    };</PRE>

<P>The class describes the storage and member functions common to both
input and output streams. The class
<A HREF="#ios"><CODE>ios</CODE></A> describes additional
common features.</P>

<P>An object of class <CODE>ios_base</CODE> stores
<B><A NAME="formatting information">formatting information</A></B>,
which consists of:</P>

<UL>
<LI><B><A NAME="format flags">format flags</A></B> in an object of type
<A HREF="#ios_base::fmtflags"><CODE>fmtflags</CODE></A></LI>

<LI>an <B><A NAME="exception mask">exception mask</A></B> in an
object of type
<A HREF="#ios_base::iostate"><CODE>iostate</CODE></A></LI>

<LI>a <B><A NAME="field width">field width</A></B> in an object of
type <I>int</I></LI>

<LI>a <B><A NAME="display precision">display precison</A></B> in an
object of type <I>int</I></LI>

<LI>a <B><A NAME="locale object">locale object</A></B>
in an object of type
<CODE><A HREF="#locale">locale</A></CODE></LI>

<LI>two <B><A NAME="extensible arrays">extensible arrays</A></B>,
with elements of type <I>long</I> and <I>void</I> pointer</LI>
</UL>

<P>An object of class <CODE>ios_base</CODE> also stores
<B><A NAME="stream state information">stream state information</A></B>,
in an object of type
<A HREF="#ios_base::iostate"><CODE>iostate</CODE></A>, and a
<B><A NAME="callback stack">callback stack</A></B>.</P>

<H3><A NAME="ios_base::event"><CODE>ios_base::event</CODE></A></H3>

<PRE>enum <B>event</B> {
    <B>copyfmt_event</B>, <B>erase_event</B>,
    <B>imbue_event</B>};</PRE>

<P>The type is an enumeration that describes an
object that can store the
<B><A NAME="callback event">callback event</A></B> used as an argument to
a function registered with
<CODE><A HREF="#ios_base::register_callback">register_callback</A></CODE>.
The distinct event values are:</P>

<UL>
<LI><CODE><A NAME="ios_base::copyfmt_event">copyfmt_event</A></CODE>,
to identify a callback that occurs near the end of a call to
<CODE><A HREF="#ios::copyfmt">copyfmt</A></CODE>, just before the
<A HREF="#exception mask">exception mask</A> is copied.</LI>

<LI><CODE><A NAME="ios_base::erase_event">erase_event</A></CODE>,
to identify a callback that occurs at the beginning of a call to
<CODE><A HREF="#ios::copyfmt">copyfmt</A></CODE>, or at
the beginning of a call to the destructor for <CODE>*this</CODE>.</LI>

<LI><CODE><A NAME="ios_base::imbue_event">imbue_event</A></CODE>,
to identify a callback that occurs at the end of a call to
<CODE><A HREF="#ios_base::imbue">imbue</A></CODE>, just before the
function returns.</LI>
</UL>

<H3><A NAME="ios_base::event_callback">
<CODE>ios_base::event_callback</CODE></A></H3>

<PRE>typedef void *(<B>event_callback</B>(event ev,
        ios_base&amp; iosbase, int idx);</PRE>

<P>The type describes a pointer to a function that can
be registered with
<CODE><A HREF="#ios_base::register_callback">register_callback</A></CODE>.
Such a function must not throw an exception.</P>

<H3><A NAME="ios_base::failure"><CODE>ios_base::failure</CODE></A></H3>

<PRE>class <B>failure</B> : public <A HREF="exceptio.html#exception">exception</A> {
public:
    explicit failure(const string&amp; what_arg) {
    };</PRE>

<P>The member class serves as the base class
for all exceptions thrown by the member function
<CODE><A HREF="#ios::clear">clear</A></CODE> in template class
<A HREF="#ios"><CODE>ios</CODE></A>. The value returned by
<CODE><A HREF="exceptio.html#exception::what">what</A>()</CODE> is
<CODE>what_arg.<A HREF="string2.html#string::data">data</A>()</CODE>.</P>

<H3><A NAME="ios_base::flags"><CODE>ios_base::flags</CODE></A></H3>

<PRE>fmtflags <B>flags</B>() const;
fmtflags <B>flags</B>(fmtflags newfmtflags);</PRE>

<P>The first member function returns the stored
<A HREF="#format flags">format flags</A>. The second member function
stores <CODE>newfmtflags</CODE> in the format flags and returns its previous
stored value.</P>

<H3><A NAME="ios_base::fmtflags"><CODE>ios_base::fmtflags</CODE></A></H3>

<PRE>typedef T1 <B>fmtflags</B>;
static const fmtflags <B>boolalpha</B>, <B>dec</B>, <B>fixed</B>, <B>hex</B>,
    <B>internal</B>, <B>left</B>, <B>oct</B>, <B>right</B>, <B>scientific</B>,
    <B>showbase</B>, <B>showpoint</B>, <B>showpos</B>, <B>skipws</B>, <B>unitbuf</B>,
    <B>uppercase</B>, <B>adjustfield</B>, <B>basefield</B>, <B>floatfield</B>;</PRE>

<P>The type is a <A HREF="lib_cpp.html#bitmask type">bitmask type</A>
<CODE>T1</CODE> that describes an object that can store
<A HREF="#format flags">format flags</A>. The distinct flag values (elements) are:</P>

<UL>
<LI><CODE><A NAME="ios_base::boolalpha">boolalpha</A></CODE>, to insert or
extract objects of type <I>bool</I> as names (such as <CODE>true</CODE>
and <CODE>false</CODE>) rather than as numeric values</LI>

<LI><CODE><A NAME="ios_base::dec">dec</A></CODE>, to insert or extract
integer values in decimal format</LI>

<LI><CODE><A NAME="ios_base::fixed">fixed</A></CODE>, to insert
floating-point values in fixed-point format (with no exponent field)</LI>

<LI><CODE><A NAME="ios_base::hex">hex</A></CODE>, to insert or extract
integer values in hexadecimal format</LI>

<LI><CODE><A NAME="ios_base::internal">internal</A></CODE>,
to pad to a <A HREF="#field width">field width</A>
as needed by inserting <A HREF="#fill character">fill
characters</A> at a point internal to a generated numeric field</LI>

<LI><CODE><A NAME="ios_base::left">left</A></CODE>,
to pad to a <A HREF="#field width">field width</A> as needed
by inserting <A HREF="#fill character">fill characters</A>
at the end of a generated field (left justification)</LI>

<LI><CODE><A NAME="ios_base::oct">oct</A></CODE>, to insert or extract
integer values in octal format</LI>

<LI><CODE><A NAME="ios_base::right">right</A></CODE>,
to pad to a <A HREF="#field width">field width</A>
as needed by inserting <A HREF="#fill character">fill characters</A>
at the beginning of a generated field (right justification)</LI>

<LI><CODE><A NAME="ios_base::scientific">scientific</A></CODE>, to insert
floating-point values in scientific format (with an exponent field)</LI>

<LI><CODE><A NAME="ios_base::showbase">showbase</A></CODE>, to insert a
prefix that reveals the base of a generated integer field</LI>

<LI><CODE><A NAME="ios_base::showpoint">showpoint</A></CODE>, to insert a
decimal point unconditionally in a generated floating-point field</LI>

<LI><CODE><A NAME="ios_base::showpos">showpos</A></CODE>, to insert a plus
sign in a non-negative generated numeric field</LI>

<LI><CODE><A NAME="ios_base::skipws">skipws</A></CODE>, to skip leading
<A HREF="lib_prin.html#white space">white space</A> before certain
extractions</LI>

<LI><CODE><A NAME="ios_base::unitbuf">unitbuf</A></CODE>, to flush output
after each insertion</LI>

<LI><CODE><A NAME="ios_base::uppercase">uppercase</A></CODE>, to insert
uppercase equivalents of lowercase letters in certain insertions</LI>
</UL>

<P>In addition, several useful values are:</P>

<UL>
<LI><CODE><A NAME="ios_base::adjustfield">adjustfield</A></CODE>,
<CODE>internal | left | right</CODE></LI>

<LI><CODE><A NAME="ios_base::basefield">basefield</A></CODE>,
<CODE>dec | hex | oct</CODE></LI>

<LI><CODE><A NAME="ios_base::floatfield">floatfield</A></CODE>,
<CODE>fixed | scientific</CODE></LI>
</UL>

<H3><A NAME="ios_base::getloc"><CODE>ios_base::getloc</CODE></A></H3>

<PRE>locale <B>getloc</B>() const;</PRE>

<P>The member function returns the stored
locale object.</P>

<H3><A NAME="ios_base::imbue"><CODE>ios_base::imbue</CODE></A></H3>

<PRE>locale <B>imbue</B>(const locale&amp; loc);</PRE>

<P>The member function stores <CODE>loc</CODE> in the
locale object, then reports the
<A HREF="#callback event">callback event</A>
<CODE><A HREF="#ios_base::imbue_event">imbue_event</A></CODE>.
It returns the previous stored value.</P>

<H3><A NAME="ios_base::Init"><CODE>ios_base::Init</CODE></A></H3>

<PRE>class <B>Init</B> {
    };</PRE>

<P>The nested class describes an object whose construction ensures that
the standard iostreams objects are properly
<A HREF="iostream.html#constructing iostreams">constructed</A>, even
before the execution of a constructor for an arbitrary static object.</P>

<H3><A NAME="ios_base::ios_base"><CODE>ios_base::ios_base</CODE></A></H3>

<PRE><B>ios_base</B>();</PRE>

<P>The (protected) constructor does nothing. A later call to
<CODE>ios::<A HREF="#ios::init">init</A></CODE>
<I>must</I> initialize the object before it can be safely destroyed.
Thus, the only safe use for class <CODE>ios_base</CODE> is as a base
class for template class
<CODE><A HREF="#ios">ios</A></CODE>.</P>

<H3><A NAME="ios_base::iostate"><CODE>ios_base::iostate</CODE></A></H3>

<PRE>typedef T2 <B>iostate</B>;
static const iostate <B>badbit</B>, <B>eofbit</B>, <B>failbit</B>, <B>goodbit</B>;</PRE>

<P>The type is a <A HREF="lib_cpp.html#bitmask type">bitmask type</A>
<CODE>T2</CODE> that describes an object that can store
<A HREF="#stream state information">stream state information</A>. The
distinct flag values (elements) are:</P>

<UL>
<LI><CODE><A NAME="ios_base::badbit">badbit</A></CODE>, to record a loss of
integrity of the stream buffer</LI>

<LI><CODE><A NAME="ios_base::eofbit">eofbit</A></CODE>, to record
end-of-file while extracting from a stream</LI>

<LI><CODE><A NAME="ios_base::failbit">failbit</A></CODE>, to record a
failure to extract a valid field from a stream</LI>
</UL>

<P>In addition, a useful value is:</P>

<UL>
<LI><CODE><A NAME="ios_base::goodbit">goodbit</A></CODE>, no bits set</LI>
</UL>

<H3><A NAME="ios_base::iword"><CODE>ios_base::iword</CODE></A></H3>

<PRE>long&amp; <B>iword</B>(int idx);</PRE>

<P>The member function returns a reference to element
<CODE>idx</CODE> of the
<A HREF="#extensible arrays">extensible array</A> with elements of type
<I>long.</I> All elements are effectively present and initially store
the value zero. The returned reference is invalid after the next call to
<CODE>iword</CODE> for the object, after the object is altered by a call to
<CODE>ios::<A HREF="#ios::copyfmt">copyfmt</A></CODE>, or
after the object is destroyed.</P>

<P>If <CODE>idx</CODE> is negative, or if unique storage is unavailable
for the element, the function calls
<CODE><A HREF="#ios::setstate">setstate</A>(badbit)</CODE>
and returns a reference that might not be unique.</P>

<P>To obtain a unique index, for use across all objects of type
<CODE>ios_base</CODE>, call
<CODE><A HREF="#ios_base::xalloc">xalloc</A></CODE>.</P>

<H3><A NAME="ios_base::openmode"><CODE>ios_base::openmode</CODE></A></H3>

<PRE>typedef T3 <B>openmode</B>;
static const openmode <B>app</B>, <B>ate</B>, <B>binary</B>, <B>in</B>, <B>out</B>, <B>trunc</B>;</PRE>

<P>The type is a <A HREF="lib_cpp.html#bitmask type">bitmask type</A>
<CODE>T3</CODE> that describes an object that can store the
<B><A NAME="opening mode">opening mode</A></B> for several iostreams
objects. The distinct flag values (elements) are:</P>

<UL>
<LI><CODE><A NAME="ios_base::app">app</A></CODE>, to seek to the end of a
stream before each insertion</LI>

<LI><CODE><A NAME="ios_base::ate">ate</A></CODE>, to seek to the end of a
stream when its controlling object is first created</LI>

<LI><CODE><A NAME="ios_base::binary">binary</A></CODE>, to read a file as a
<A HREF="lib_file.html#binary stream">binary stream</A>,
rather than as a
<A HREF="lib_file.html#text stream">text stream</A></LI>

<LI><CODE><A NAME="ios_base::in">in</A></CODE>,
to permit extraction from a stream</LI>

<LI><CODE><A NAME="ios_base::out">out</A></CODE>,
to permit insertion to a stream</LI>

<LI><CODE><A NAME="ios_base::trunc">trunc</A></CODE>, to truncate an
existing file when its controlling object is first created</LI>
</UL>

<H3><A NAME="ios_base::operator="><CODE>ios_base::operator=</CODE></A></H3>

<PRE>ios_base&amp; <B>operator=</B>(const ios_base&amp; right);</PRE>

<P>The operator copies the stored
<A HREF="#formatting information">formatting information</A>,
making a new copy of any
<A HREF="#extensible arrays">extensible arrays</A>.
It then returns <CODE>*this</CODE>. Note that the
<A HREF="#callback stack">callback stack</A> is <I>not</I> copied.</P>

<H3><A NAME="ios_base::precision"><CODE>ios_base::precision</CODE></A></H3>

<PRE>streamsize <B>precision</B>() const;
streamsize <B>precision</B>(streamsize newprecision);</PRE>

<P>The first member function returns the stored
<A HREF="#display precision">display precision</A>. The second member
function stores <CODE>newprecision</CODE> in the display precision and returns
its previous stored value.</P>

<H3><A NAME="ios_base::pword"><CODE>ios_base::pword</CODE></A></H3>