CS50x 2026 - Lecture 5 - Data Structures

All right, this is CS 50, and this is week 5 already, wherein we will focus today on data structures, which is a topic we touched on a little bit in in simple form, but today we'll dive all the more deeply and for better or for worse, this is our last week on C.

Uh, next week, of course, we transition to Python, which is a so-called higher level programming language, which is really, frankly, just going to make our lives a lot easier. We're going to be able to solve a lot of the same problems, but so much more quickly as Humans, but not necessarily as we'll see as fast when we run the code as the

computer might have if we were still using a lower level language like C. So indeed thematic over this week and next is going to be the theme that we've seen before of trade-offs. But before we get there, why don't we focus on a couple of data structures that you might encounter in the real world,

namely stacks and cues. Let's learn some facts about both of these if we could dim the lights dramatically.

Once upon a time there was a guy named Jack. When it came to making friends, Jack did not have the knack. So Jack went to talk to the most popular guy he knew. He went up to Lou and asked, What do I do? Lou saw that his friend was really distressed. Well, Lou began,

Just look how you're dressed. Don't you have any clothes with a different look? Yes, said Jack, I sure do. Come to my house and I'll show them to you. So they went off the jacks, and Jack showed Lou the box where he kept all his shirts and his pants and his socks. Lou said,