明确指定模板参数或者推导出来

// explicit_specialization.cpp
template<class T> void f(T t)
{
};

// Explicit specialization of f with 'char' with the
// template argument explicitly specified:
//
template<> void f<char>(char c)
{
}

// Explicit specialization of f with 'double' with the
// template argument deduced:
//
template<> void f(double d)
{
}
int main()
{
}