C++ 模板 - 多种类型
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C++ Template - Multiple types
提问by SysAdmin
consider the following template class.
考虑以下模板类。
template <class T>
class MyClass
{
void MyFunc();
}
template <class T>
void MyClass<T>::MyFunc()
{
//...implementation goes here
}
I need to add another function MyFunc2which accepts an additional Template arg T2i.e
我需要添加另一个函数MyFunc2，它接受一个额外的模板 arg T2即
template <class T>
class MyClass
{
void MyFunc();
template <class T2>
static void MyFunc2(T2* data);
}
template <class T>
void MyClass<T>::MyFunc()
{
//...implementation goes here
}
template <class T, class T2>
void MyClass<T>::MyFunc2(T2* pData)
{
//...implementation goes here
}
I am using VS 2008 compiler. I am getting the error
我正在使用 VS 2008 编译器。我收到错误
error C2244: unable to match function definition to an existing declaration
How should the the functions definition and declaration look like in this case.
在这种情况下，函数定义和声明应该如何。
采纳答案by Chubsdad
template <class T>
template <class T2>
void MyClass<T>::MyFunc2(T2* pData)
{
//...implementation goes here
}
EDIT 2:
编辑2：
$14.5.2/1 - "A template can be declared within a class or class template; such a template is called a member template. A member template can be defined within or outside its class definition or class template definition. A member template of a class template that is defined outside of its class template definition shall be specified with the template-parameters of the class template followed by the template-parameters of the member template."
$14.5.2/1 - “可以在类或类模板中声明模板；这样的模板称为成员模板。可以在其类定义或类模板定义之内或之外定义成员模板。在其类模板定义之外定义的类模板应使用类模板的模板参数指定，后跟成员模板的模板参数。”
回答by bobobobo
What you're doing is fine, try this out:
你在做什么很好，试试这个：
template <typename S,typename T>
struct Structure
{
S s ;
T t ;
} ;
int main(int argc, const char * argv[])
{
Structure<int,double> ss ;
ss.s = 200 ;
ss.t = 5.4 ;
return 1;
}
This code works. If you're getting strange errors, see if you forward declaredStructureusing only 1 template parameter (that's what I was doing).
此代码有效。如果您遇到奇怪的错误，请查看您是否仅使用 1 个模板参数进行了转发声明Structure（这就是我正在做的）。
回答by Hafedh
Try this one :
试试这个：
template <class T, class T2>
class MyClass
{
public:
static void MyFunc2(T2* data);
};
template <class T, class T2>
void MyClass<T, T2>::MyFunc2(T2* pData)
{
cout << "dummy " << *pData<< "\n";
}
Then
然后
int main()
{
cout << "Hello World!\n";
MyClass<int, int> a;
int *b = (int*)malloc(sizeof(int));
*b = 5;
a.MyFunc2(b);
}
Output
输出
Hello World!
dummy 5
