cin对象如何根据用户需要将字符转换为不同类型? [英] How does cin object converts characters to different types as user needes?

问题描述

当 std :: cin 对象是 basic_istream< char> ( istream )的实例时，如何处理不同类型的对象?

How does std::cin object deal with different types while it is an instance of basic_istream<char> (istream)?

推荐答案

类 std :: basic_istream< CharT，Traits> 对类型为 CharT .它为该输入流提供了相对较低级别的访问和相对较高级别的访问.例如，您可以调用 std :: cin.get()以便从输入流中检索下一个字符.这将始终返回 CharT ，因为这是流中字符的基础类型.但是， basic_istream 还提供了 formatted输入函数，其目的是将字符流解释为某种类型的编码，可能是 int ， std :: basic_string< CharT，Traits> 或其他内容.因此，虽然流不由 int 组成，但是有一个 operator>> 通过从中连续读取数字来提取 int 值. char 流并将其解释为整数的以10为底的表示形式. operator>> 函数已重载，因此可以用来提取各种不同的类型.

The class std::basic_istream<CharT, Traits> models an input stream of characters of type CharT. It provides both relatively low-level and relatively high-level access to that input stream. You can, for example, call std::cin.get() in order to retrieve the next character from the input stream; this will always return CharT, since that's the underlying type of characters in the stream. However, basic_istream also provides the formatted input functions, whose purpose is to interpret that character stream as an encoding of some type, which could potentially be int, std::basic_string<CharT, Traits>, or something else. Thus, while the stream does not consist of ints, there is an operator>> that extracts an int value by reading digits successively from a char stream and interpreting them as the base-10 representation of an integer. The operator>> function is overloaded so that it can be used to extract various different types.

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