c ++模板和头文件 [英] c++ template and header files

问题描述

所以我听说c ++模板不应该分为.h和.cpp ...

so I heard that c++ templates shouldn't be separated into a .h and .cpp...

，例如一个这样的模板：

for instance a template like this:

template <class T>
class J{

   T something;

}

这是真的吗？为什么会这样？

is this true? why is it so?

如果因为这样我就必须将声明和实现放在同一个文件中，我应该把它放在.h文件还是一个.cpp文件？

if because of that I'm gonna have to put both declaration and implementation in the same file, should I put it in a .h file or a .cpp file?

推荐答案

标题

这是因为模板在编​​译时被实例化，时间，而不是链接时间和不同的翻译单位（大致相当于您的 .cpp 文件）只在链接时彼此了解。标题在编译时往往被广泛的知道，因为您需要在任何需要它们的翻译单元中 #include 。

It's because templates are instantiated at compile-time, not link-time, and different translation units (roughly equivalent to your .cpp files) only "know about" each other at link-time. Headers tend to be widely "known about" at compile-time because you #include them in any translation unit that needs them.

阅读 https://isocpp.org/wiki/faq/templates 了解更多信息。

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