标准库
流是什么？
在c中引入了流（stream）的概念。它将数据的输入输出看作是数据的流入流出，这样不管是磁盘文件或者是物理设备（打印机，显示器，键盘），都可以看作一种流的源和目的，视他们为同一种东西，而不管其具体的物理结构，即对他们的操作，就是数据的流入和流出。 在C中流可分为两大类，即文本流（text stream）和二进制流（binary stream）。所谓的文本流是指在流中流动的数据是以字符形式出现的
A bitstream (or bit stream), also known as binary sequence, is a sequence of bits. A bytestream is a sequence of bytes. Typically, each byte is from a range of 256 distinct values (octets), and so the term octet stream is sometimes used to refer to the same thing. An octet may be encoded as a sequence of 8 bits in multiple different ways (see endianness) so there is no unique and direct translation between bytestreams and bitstreams.
Bitstreams and bytestreams are used extensively in telecommunications and computing. For example, Synchronous Digital Hierarchy transports synchronous bitstreams, and Transmission Control Protocol transports an asynchronous bytestream.比特流和字节流被广泛地用于电信和计算。 例如，同步数字体系传输同步比特流，传输控制协议传输异步字节流。