C++14 Generic Lambdas: A Beginner's Guide 🎯

Welcome to our comprehensive guide on C++14 Generic Lambdas! This lesson is designed for both beginners and intermediates, so sit back, relax, and let's dive into the world of functional programming in C++. 💡

What are Lambdas? 📝

Lambdas, or anonymous functions, are a modern feature of C++ that allows you to create small, one-off functions without having to name them. They are a powerful tool for writing cleaner, more efficient code.

cpp

[capture](parameters) -> return_type { function_body }

This is the syntax for a lambda function in C++. Let's break it down:

[capture]: This is the capture clause, which defines what the lambda function can access from its surrounding context.
(parameters): Just like a regular function, lambdas can take parameters.
-> return_type: This is the return type of the lambda function. If not specified, the return type is auto.
{ function_body }: This is the body of the lambda function, enclosed in curly braces {}.

C++14 Generic Lambdas 📝

With C++14, we have the concept of generic lambdas, which allows us to specify template parameters for our lambdas. This makes them more versatile and reusable.

cpp

auto my_lambda = [](auto x, auto y) { return x + y; };

In the example above, my_lambda is a generic lambda that takes two template parameters x and y and returns their sum. The auto keyword before the function signature allows the compiler to infer the types of x and y.

Practical Examples 💡

Example 1: Sorting a Vector

Let's create a generic lambda that sorts a std::vector of any type.

cpp

template <typename T>
void sort_vector(std::vector<T>& vec, const T& compare) {
    std::sort(vec.begin(), vec.end(), [=](const T& a, const T& b) {
        return compare(a, b) < 0;
    });
}

In this example, we have a function sort_vector that takes a std::vector and a comparison function. The lambda inside the std::sort function uses the comparison function to sort the vector.

Example 2: Filtering a Vector

Now, let's create another generic lambda that filters a std::vector based on a condition.

cpp

template <typename T>
std::vector<T> filter_vector(std::vector<T>& vec, const T& filter) {
    std::vector<T> result;
    for (const auto& item : vec) {
        if (filter(item)) {
            result.push_back(item);
        }
    }
    return result;
}

In this example, we have a function filter_vector that takes a std::vector and a filter function. The lambda inside the loop uses the filter function to decide whether to add an item to the result vector.

C++14 Generic Lambdas: A Beginner's Guide 🎯

C++14 Generic Lambdas: A Beginner's Guide 🎯

What are Lambdas? 📝

C++14 Generic Lambdas 📝

Practical Examples 💡

Example 1: Sorting a Vector

Example 2: Filtering a Vector

Quiz 📝