不是個抽象類,但是他是C++流的基類.它提供了基本的緩沖區管理.它包含六個緩存區指針,三個分別是讀指針(開頭,結尾,當前),另外三個是寫指針(開頭,結尾,當前)
讀開始指針 當前讀指針 讀結尾指針
_M_gbegin _M_gnext _M_gend
=========================================================
^ ^ ^
_M_pbegin _M_pnext _M_pend
寫開始指針 當前寫指針 寫結尾指針
template <class_CharT, class_Traits>
classbasic_streambuf
{
friendclassbasic_istream<_CharT, _Traits>;
friendclassbasic_ostream<_CharT, _Traits>;
public: // Typedefs.
typedef_CharT char_type;
typedeftypename_Traits::int_type int_type;
typedeftypename_Traits::pos_type pos_type;
typedeftypename_Traits::off_type off_type;
typedef_Traits traits_type;
public: // Destructor.
virtual ~basic_streambuf() {}
public: // Locale-related functions.
localepubimbue(constlocale& __loc) {
this->imbue(__loc);
locale__tmp = _M_locale;
_M_locale = __loc;
return__tmp;
}
localegetloc() const { return_M_locale; }
public: // Buffer management.
//設置緩沖區和長度
basic_streambuf* pubsetbuf(char_type* __s, streamsize__n)
{ returnthis->setbuf(__s, __n); }
//設置緩沖區偏移量,簡單調用seekoff()函數
pos_typepubseekoff(off_type__offset, ios_base::seekdir__way,
ios_base::openmode__mod = ios_base::in | ios_base::out)
{ returnthis->seekoff(__offset, __way, __mod); }
//設置緩沖區位置,簡單調用seekpos()函數
pos_typepubseekpos(pos_type__sp,
ios_base::openmode__mod = ios_base::in | ios_base::out)
{ returnthis->seekpos(__sp, __mod); }
//放置緩沖區同步,簡單調用sync()函數
intpubsync() { returnthis->sync(); }
延伸閱讀
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