What are the differences between std::function and lambda in C++?

What are the differences between std::function and lambda in C++?

In C++, std::function is a general-purpose polymorphic function wrapper, while a lambda is an inline, anonymous function.

Can you give me an example of how to use both?

Sure! Here's a simple example:

Using std::function:

#include <functional>
#include <iostream>

void execute(std::function<void()> func) {
    func();
}

int main() {
    std::function<void()> myFunc = []() { std::cout << "Hello from std::function!"; };
    execute(myFunc);
}

Using a lambda directly:

#include <iostream>

int main() {
    auto myLambda = []() { std::cout << "Hello from lambda!"; };
    myLambda();
}

What are the performance implications of using one over the other?

Lambdas can be more efficient since they avoid the overhead of type erasure that std::function incurs. However, std::function is more flexible.

When should I prefer using std::function?

You should prefer std::function when you need to store or pass around callable objects with different types, especially in APIs.