C++：iostream 的使用
std::iostream
Input/output stream
- ios_base
- ios
- istream
- ostream
- iostream
- fstream
- stringstream
[NOTE: 这里是 iostream 类，若想了解 iostream 库，请看 Input/Output library.]
该类内部所有成员继承自 istream类和 ostream类，因此能进行输入和输出的操作。
该类依赖于单一 streambuf 对象进行输入输出操作。
该类保存一个继承自ios_base, ios and istream的内部字段集合。
公共成员函数继承自 istream
(public member function )
operator>>
提取格式化输入
gcount
获取字符串长度，统计char字符数量
get
从流中提取字符，作为未格式化的输入
getline
从流中提取字符直到遇到分隔字符
ignore
提取特定字符并丢弃
peek
提取下一个字符，并放回
read
提取若干个字符并存入数组
readsome
从缓冲区提取若干个字符并存入数组
putback
Put character back (public member function )
unget
Unget character (public member function )
tellg
返回输入流中当前字符的位置
seekg
设置要从输入流中提取的下一个字符的位置
sync
从标准输入的字符buffer中删除任何未读的字符
公共成员函数继承自 ostream
(public member function )
operator<<
插入格式化输出
put
将字符c插入流中
write
将s指向的数组的前n个字符插入到流中
tellp
获取要将下一个字符插入输出流的位置
seekp
设置要将下一个字符插入输出流的位置
flush
刷新输出流缓冲区
公共成员函数继承自 ios
(public member function )
good
检查 stream 的状态是否正常
eof
检查是否设置了eofbit，即是否正常读到文件结尾
fail
检查是否设置了failbit或badbit，即非正常结束
bad
检查是否设置了badbit，即非正常结束
operator!
评估流打开状态，如果返回为true即设置了failbit或badbit
operator bool (C++11)
评估流打开状态，如果返回为true即设置了goodbit
rdstate
获取错误状态flags
setstate
设置错误状态flag
clear
清除flags
copyfmt
复制对应格式信息
fill
获取/设置填充字符
exceptions
Get/set exceptions mask (public member function )
imbue
Imbue locale (public member function )
tie
Get/set tied stream (public member function )
rdbuf
Get/set stream buffer (public member function )
narrow
Narrow character (public member function )
widen
Widen character (public member function )
公共成员函数继承自 ios_base
(public member function )
flags
获取/设置格式标志
setf
设置特定格式标志
unsetf
清除特定格式标志
precision
获取/设置浮点小数精度
width
获取/设置字段宽度
imbue
Imbue locale (public member function )
getloc
Get current locale (public member function )
xalloc
Get new index for extensible array [static] (public static member function )
iword
Get integer element of extensible array (public member function )
pword
Get pointer element of extensible array (public member function )
register_callback
Register event callback function (public member function )
sync_with_stdio
Toggle synchronization with cstdio streams [static] (public static member function )