argument（实参）
A value passed to a function when it is called.
传递给被调用函数的值。
block（块）
Sequence of statements enclosed in curly braces.
花括号括起来的语句序列。
buffer（缓冲区）
A region of storage used to hold data. IO facilities
often store input (or output) in a buffer and read or
write the buffer independently of actions in the program.
Output buffers usually must be explicitly flushed to
force the buffer to be written. By default, reading cin
flushes cout; cout is also flushed when the program ends
normally.
一段用来存放数据的存储区域。IO 设备常存储输入（或输出）到
缓冲区，并独立于程序动作对缓冲区进行读写。输出缓冲区通常
必须显式刷新以强制输出缓冲区内容。默认情况下，读 cin 会刷
新 cout；当程序正常结束时，cout 也被刷新。
built-in type（内置类型）
A type, such as int, defined by the language.
C++ 语言本身定义的类型，如 int。
cerr
ostream object tied to the standard error, which is often
the same stream as the standard output. By default,
writes to cerr are not buffered. Usually used for error
messages or other output that is not part of the normal
logic of the program.
绑定到标准错误的 ostream 对象，这通常是与标准输出相同的
流。默认情况下，输出 cerr 不缓冲，通常用于不是程序正常逻
辑部分的错误信息或其他输出。
cin
istream object used to read from the standard input.
用于从标准输入中读入的 istream 对象。
class
C++ mechanism for defining our own data structures. The
class is one of the most fundamental features in C++.
Library types, such as istream and ostream, are classes.
