A discovery
I found a case that struck me.
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| template <class T>
struct temp {
T value;
};
template <class T, class... Ts>
struct temp {
temp<T> value_temp;
temp<Ts...> rest_temps;
};
|
It can’t pass compiling with a error message - Too many template parameters in template redeclaration.
It would work if we changed it as below:
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| template <class T, class... Ts>
struct temp;
template <class T>
struct temp<T> {
T value;
};
template <class T, class... Ts>
struct temp {
temp<T> value_temp;
temp<Ts...> rest_temps;
};
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The declaration with multiple parameters certainly can be placed at the beginning, as long as you like. :)
Accumulate the parameters in the template
I wrote the below code to practice template specialization.
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| #include <iostream>
template <int i, int... Args>
struct Sum {
static constexpr int value = i + Sum<Args...>::value;
};
template <int i>
struct Sum<i> {
static constexpr int value = i;
};
int main() {
std::cout << Sum<1, 2, 3>::value << std::endl;
return 0;
}
|
Minimum value
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| #include <iostream>
template <int i, int... args>
struct Min {
private:
static constexpr int tmp = Min<args...>::value;
public:
static constexpr int value = i < tmp ? i : tmp;
};
template <int i>
struct Min<i> {
static constexpr int value = i;
};
int main() {
std::cout << Min<1, 2, 3>::value << std::endl;
return 0;
}
|