Inexplicable C + + errors

Question

The code is as follows：

include<iostream>

include<cmath>

using namespace std;
template<class T, class A, class...Q>
class Math {
public:
Math() {};
Math(T t, A a, Q...q) {
if (t > a)
{
l[index] = t;
l[index + 1] = a;
};

};
template<class V>
auto guide(string* p, V v) {
    auto i = v;
    switch (p)
    {
    case "cos":
        i = cos(v);
        break;
    case "sin":
        i = sin(v);
    case "sqrt":
        i = sqrt(v);
        break;
    case "tan":
        i = tan(v);
    default:
        return i;
        break;
    };
    return i;
}

int index = 0;

private:
T l[900]=0;
};

int main() {
Math<int, int, int>p(12, 14, 15);

}
//It can't work

Answer 1

It's generally recommended to be somewhat clearer when you ask a question than "It can't work", but anyhow, try changing the line to:

T l[900]={0};