做模板 <typename T> 每个模板函数需要声明吗？

Question

For a class with multiple template functions does template have to be included in each declaration like so:

class Foo
{
    public:
        template <typename T>
        void foo(T a);

        template <typename T>
        void bar(T b);
}

Or can you just include template <typename T> for the first declaration like so:

class Foo
{
    public:
        template <typename T>
        void foo(T a);
        void bar(T b);
}

I suspect only the first one is valid since without the ; it makes me think the declaration is actually template <typename T> void foo(T a) if written on one line. I assume its just convention to separate it into two lines! Looking for confirmation.

Answer 1

The template specifier must appear before each templated function. Your second example will cause an error that T is not a recognized type for bar , since template <typename T> applies only to foo in this case.

Alternatively, if you wanted to use the same type for each function in a class, you could declare the entire class as a template:

template <typename T>
class Foo
{
public:
    void foo(T a);
    void bar(T b);
};