c++缓冲区是怎么回事的哦？是怎么把输入输出存入缓冲区的哦？平时直接cout就打印结果了啊，没体会到怎么属于缓冲了的

Answer 1

Cout is a row-level buffer, and it will be flushed once it encounters a newline character. However, the cout object will also be flushed once when it is destroyed. In your example, the cout object needs to be destroyed once before returning 0.
In terms of cerr, I have forgotten what it said in APUE. After debugging, I found that there is no buffering...

Answer 2

You will experience it when you are multi-threaded. If the cache is not cleared, the logs of thread A may be printed on thread B