问题
I get this error a LOT, and i never know why. Can someone help me find the cause of it?
Edit:Removed code
回答1:
Put the implementation (your method definitions) into the header along with the class declaration (see this in the C++ FAQ). Some compilers have supported an "export" keyword for doing it the way that you did, but that has been nixed in the C++0x.
回答2:
Templates must be defined in header files. See these FAQs for more info:
- Why can't I separate the definition of my templates class from its declaration and put it inside a .cpp file?
- How can I avoid linker errors with my template functions?
回答3:
This errors are happening because, your template definitions are not visible to the user code. Template definition should be declared in,
- Header file, along with the template declarations
- In the .cpp file, where the user code uses it. However in this approach the definition will be visible only to the .cpp which uses it. See below example
test.h
template<typename T>
void foo (T*);
test.cpp
int main ()
{
foo(1);
}
template<typename T>
void foo (T *p)
{
...
}
test2.cpp
// This file can not see the definition of foo
来源：https://stackoverflow.com/questions/5776862/template-class-unresolved-external-symbols