Templates in C++

Templates are a powerful feature in C++ that allow functions and classes to operate with generic types. This means you can write a function or class to work with any data type, without having to rewrite it for each type.

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1. What are Templates?

Templates in C++ allow you to create generic functions and generic classes. You can define a function or class once and use it with different data types without rewriting it for each one.

Types of Templates:

1. Function Templates
2. Class Templates

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2. Function Templates

A function template works with any data type. You can write a function template that works for int, float, double, or any other type.

Syntax of a Function Template:

template <typename T>
T function_name(T arg1, T arg2) {
    // Code here
}

• T is the placeholder for the data type.

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Example of a Function Template:

#include <iostream>
using namespace std;

template <typename T>
T add(T a, T b) {
    return a + b;
}

int main() {
    cout << "Sum of integers: " << add(5, 10) << endl;
    cout << "Sum of floats: " << add(5.5, 10.1) << endl;
    return 0;
}

Output:

Sum of integers: 15
Sum of floats: 15.6

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3. Class Templates

A class template allows you to create a class that can work with any data type. This is useful for creating data structures like stacks, queues, or linked lists that can handle any type of data.

Syntax of a Class Template:

template <typename T>
class ClassName {
    T variable;
public:
    ClassName(T var) : variable(var) {}
    void display() {
        cout << "Variable: " << variable << endl;
    }
};

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Example of a Class Template:

#include <iostream>
using namespace std;

template <typename T>
class Container {
    T value;
public:
    Container(T val) : value(val) {}
    void display() {
        cout << "Value: " << value << endl;
    }
};

int main() {
    Container<int> intContainer(42);
    Container<string> stringContainer("Hello");

    intContainer.display();
    stringContainer.display();

    return 0;
}

Output:

Value: 42
Value: Hello

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4. Template Specialization

Sometimes, you might want to provide a specific implementation of a template for a particular data type. This is called template specialization.

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Example of Template Specialization:

#include <iostream>
using namespace std;

template <typename T>
class Calculator {
public:
    T add(T a, T b) {
        return a + b;
    }
};

// Specialization for string data type
template <>
class Calculator<string> {
public:
    string add(string a, string b) {
        return a + " " + b;
    }
};

int main() {
    Calculator<int> intCalc;
    Calculator<string> stringCalc;

    cout << "Sum of integers: " << intCalc.add(5, 10) << endl;
    cout << "Concatenated strings: " << stringCalc.add("Hello", "World") << endl;

    return 0;
}

Output:

Sum of integers: 15
Concatenated strings: Hello World

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5. Advantages of Templates

1. Code Reusability: You write a generic function or class once, and use it with any data type.
2. Type Safety: Templates are type-safe and checked during compilation.
3. Flexibility: Templates allow you to create more flexible, reusable, and maintainable code.

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6. Final Thoughts

Templates in C++ offer a powerful way to create functions and classes that can work with any data type. They help in writing generic, reusable code and are a key feature in modern C++ programming.

Happy coding!