C++ Templates: Function & Class Templates for High-Performance Generic Code

Templates are the foundation of Generic Programming in C++. A template allows you to write a single blueprint for a function or class that works seamlessly across any data type without duplicating code.

1. Function Template Example

#include <iostream>
#include <string>

// Generic template function
template <typename T>
T getMaximum(T a, T b) {
    return (a > b) ? a : b;
}

int main() {
    std::cout << "Max int:    " << getMaximum(15, 42) << "\n";           // Instantiates getMaximum<int>
    std::cout << "Max double: " << getMaximum(3.14, 2.71) << "\n";       // Instantiates getMaximum<double>
    std::cout << "Max string: " << getMaximum<std::string>("Apple", "Zebra") << "\n"; // Zebra
    return 0;
}

2. Generic Class Template

#include <iostream>

template <typename T, int Capacity>
class FixedStack {
private:
    T elements[Capacity];
    int topIndex = -1;

public:
    void push(const T& item) {
        if (topIndex < Capacity - 1) {
            elements[++topIndex] = item;
        }
    }
    T pop() {
        return elements[topIndex--];
    }
};

int main() {
    FixedStack<int, 10> intStack;
    intStack.push(100);
    std::cout << "Popped: " << intStack.pop() << "\n";
    return 0;
}