1. 静态类型(Statically Typed)：A language in which types are fixed at compile time. Most statically typed languages enforce this by requiring you to declare all variables with their datatypes before using them. Java and C are statically typed languages.

2. 动态类型(Dynamically Typed)：A language in which types are discovered at execution time; the opposite of statically typed. VBScript and Python are dynamically typed, because they figure out what type a variable is when you first assign it a value.

3. 强类型(Explicit Typed)：A language in which types are always enforced. Java and Python are strongly typed. If you have an integer, you can't treat it like a string without explicitly converting it.

4. 弱类型(Implicit Typed)：A language in which types may be ignored; the opposite of strongly typed. VBScript is weakly typed. In VBScript, you can concatenate the string '12' and the integer 3 to get the string '123', then treat that as the integer 123, all without any explicit conversion.

下边再说下一个与语言类型相关的概念叫鸭子类型(Duck Typing)，什么是鸭子类型呢？

“When I see a bird that walks like a duck and swims like a duck and quacks like a duck, I call that bird a duck.”当看到一只鸟走起来像鸭子、游泳起来像鸭子、叫起来也像鸭子，那么这只鸟就可以被称为鸭子。

“ In other words, don't check whether it IS-a duck: check whether it QUACKS-like-a duck, WALKS-like-a duck, etc, depending on exactly what subset of duck-like behaviour you need to play your language-games with.”换句话说，不管它是不是鸭子，而要看它像不像鸭子，取决于它到底有没有需要的鸭子一样的行为子集。即便它是一只学鸭叫鸭走鸭游的变态鸡也可以称它鸭子，说白了它默许不同类型的对象出现在同一位置，像多态一样工作却没有继承。

鸭子类型是动态类型和某些静态语言的一种对象推断风格，本身不关注对象的类型，而在乎对象的行为(对象的方法)，如果对象调用的方法不存在，将引发一个运行时错误。所以说上文讲的相似性没有明确的边界，到底多像才能称鸭子其实不是一个问题，甚至可能只要你能叫能跑走能游就成，具体怎么叫怎么走怎么游都无所谓。因为猪是会叫会走还能游的，所以在某些场景下猪也可被称为鸭子。

转载于:https://www.cnblogs.com/XiongMaoMengNan/p/7604013.html

原文链接：https://blog.csdn.net/weixin_30342827/article/details/98046357

本站声明:网站内容来源于网络,如有侵权,请联系我们,我们将及时处理。