How do lambda expressions capture variables by reference in C++?

Can you explain how lambda expressions capture variables by reference in C++?

Sure! In C++, lambda expressions can capture variables by reference using the [&] capture clause. This allows the lambda to access and modify the original variables.

What happens if the captured variable goes out of scope?

If the captured variable goes out of scope, the lambda will have a dangling reference, which can lead to undefined behavior if accessed.

Can you give me an example of a lambda expression capturing by reference?

Absolutely! Here's a simple example:

int x = 10;
auto lambda = [&x]() { x += 5; };
lambda(); // x is now 15

Are there any performance implications of capturing by reference?

Capturing by reference can be more efficient than capturing by value, as it avoids copying the variable. However, you must ensure the referenced variable remains valid.