关于标准IO库的缓冲

anbutu

在看APUE的时候，下面这一段没看明白，哪个达人给解释一下，谢谢！



Line buffered. In this case, the standard I/O library performs I/O when a newline character is encountered on input or output. This allows us to output a single character at a time (with the standard I/O fputc function), knowing that actual I/O will take place only when we finish writing each line. Line buffering is typically used on a stream when it refers to a terminal: standard input and standard output, for example.

Line buffering comes with two caveats. First, the size of the buffer that the standard I/O library is using to collect each line is fixed, so I/O might take place if we fill this buffer before writing a newline. Second, whenever input is requested through the standard I/O library from either (a) an unbuffered stream or (b) a line-buffered stream (that requires data to be requested from the kernel), all line-buffered output streams are flushed. The reason for the qualifier on (b) is that the requested data may already be in the buffer, which doesn't require data to be read from the kernel. Obviously, any input from an unbuffered stream, item (a), requires data to be obtained from the kernel.

雨过白鹭洲

直接看英文版啊。。