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Welcome to this bonus section for the course.

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In this section, we'll learn the basics of C++ Lambda expressions.

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Lambda expressions were first introduced in C++ 11 and then extended in C++ 14 and 17.

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They provide a very convenient way to provide functionality exactly where it's needed without writing

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lots and lots of code.

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In order to understand lambda expressions, it's important to understand what they are and what motivated

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their addition to C++.

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First, we'll look at what motivated C++ lambda expressions, and in order to do that, we'll quickly

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review using C++ function objects or functions.

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You may remember that I spoke about functions in the algorithm's lecture in the standard template library

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section of the course.

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Why is it important to understand functional objects?

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Well, because behind the scenes, the C++ compiler generates anonymous or unnamed functional objects

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from land expressions.

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Then we'll look at the syntax of a lambda expression and go through every part of it.

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Well, then see the difference between stateless and stateful lambda expressions.

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Stateless lambdas only know about the information that's passed into them via the parameter list.

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Pretty much like a regular function.

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Well then learn about stateful lambdas.

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These are a bit more complex since they can capture the elements from the environment that they execute

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in.

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So they close around their environment and that's where the concept of a closure comes from.

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This is a very, very powerful concept and happens via the lambdas capture list.

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There are lots of options here and we'll look at the ones that are most commonly used.

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Finally, we'll look at lambdas in the context of the STL.

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We've already seen basic lambdas in the STL section, but we'll look at a few more examples here.

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That's it.

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I hope you enjoyed this section.

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Please remember I'm only covering the basics of C++ lambda expressions.

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They can get very complex when we use them with templates as class functions and when we pass and return

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lambdas to and from functions.

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So let's see what motivated C++ Lambda expressions in the next video.