C++ Lambda Expressions Tutorial

Basic Syntax

// Lambda Syntax: [capture](parameters) { body }
auto add = [](int a, int b) {
    return a + b;
};
std::cout << add(2, 3); // Outputs: 5
                

Capturing Variables

You can capture variables from the surrounding scope:

int x = 10, y = 20;
auto sum = [x, y]() {
    return x + y;
};
std::cout << sum(); // Outputs: 30
                

Mutable Lambdas

To modify captured variables, use the mutable keyword:

int num = 5;
auto increment = [num]() mutable {
    return ++num;
};
std::cout << increment(); // Outputs: 6
                

Generic Lambdas

With C++14, lambdas can be made generic using auto:

auto multiply = [](auto a, auto b) {
    return a * b;
};
std::cout << multiply(3, 4.5); // Outputs: 13.5
                

Applications

• Sorting: Use lambdas for custom sorting.
• Callbacks: Provide inline functions as arguments.
• Concurrency: Combine lambdas with threading.