Templates

#include <iostream>
#include <string>
using namespace std;

// Function template
template <typename T>
T maxValue(T a, T b) {
    return (a > b) ? a : b;
}

// Class template
template <typename T, int Size>
class FixedArray {
    T data[Size];
    int count = 0;
public:
    void push(const T &value) {
        if (count < Size) data[count++] = value;
    }
    T get(int index) const { return data[index]; }
    int size() const { return count; }

    // Iterator support
    T *begin() { return data; }
    T *end() { return data + count; }
};

// Template specialization
template <typename T>
void print(const T &value) {
    cout << value << endl;
}

template <>  // Full specialization for bool
void print<bool>(const bool &value) {
    cout << (value ? "true" : "false") << endl;
}

// Variadic template (C++11)
template <typename T>
T sum(T value) { return value; }

template <typename T, typename... Args>
T sum(T first, Args... rest) {
    return first + sum(rest...);
}

int main() {
    // Function template (type deduced)
    cout << maxValue(3, 7) << endl;          // int
    cout << maxValue(3.14, 2.71) << endl;    // double
    cout << maxValue<string>("abc", "xyz") << endl; // explicit

    // Class template
    FixedArray<int, 5> nums;
    nums.push(10); nums.push(20); nums.push(30);
    for (int val : nums) cout << val << " ";

    // Specialization
    print(42);     // "42"
    print(true);   // "true" (specialized)

    // Variadic template
    cout << sum(1, 2, 3, 4, 5) << endl;  // 15

    return 0;
}