August 2021
Intermediate to advanced
450 pages
5h 35m
Chinese
Content preview from C++语言导学（原书第2版）
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5.1.2 类型转换
接受单个参数的构造函数定义了从参数类型到类类型的转换。例如，complex（参见4.2.1节）提供了一个接受double的构造函数：
这种隐式类型转换有时候很理想，有时候则不然。例如，Vector（参见4.2.2节）提供了一个接受int的构造函数：
这通常会被认为是一个不幸的结果，而且标准库vector也禁止这种int到vector的“转换”。
避免这种问题的方法是，只允许显式“类型转换”，即，我们可以像下面这样定义构造函数：
于是：
关于类型转换的问题，大多数类型与Vector类似，complex则只能代表一小部分，因此除非你有充分理由，否则最好将接受单个参数的构造函数声明为explicit的。
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