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Alright, so it's called Signed Integers, Faster and Corrector. It's about, well, I came to see lightning talks here last year. Jon Kalb gave a great talk about unsigned, he was mostly talking about the correctness and safety of sticking with signed integers. Chandler Carruth also gave a great talk and it touched upon how unsigned integers aren't always the fastest. But also there's this guy Krister Walfridsson, he was on CPP Cast a few months ago, he writes a great blog talking about GCC optimization. It's a great read, and in particular there's this one article that just goes through a bunch of ways in which signed integers can exploit undefined behavior to write, faster, more optimized, simpler, more terse code and it kind of blew my mind. So I thought I'd share it with you. I also, I've been trying to persuade other people, colleagues, people on the slack channel. That you know, signed is faster and it's difficult to persuade people. It's generally difficult to persuade people of things. And so I'm not gonna try I just wanna share these cool optimizations but I will have a quick round-a-bout, you know, undefined behavior, contracts that kind of thing. Because it is a fundamentally difficult thing to explain to people. Contracts because they have more than one human in them are a necessarily complicated thing. And when people look at contracts, you know, which bit of this line do you think I'm going to bring up here, really. The const keyword. Now I've got a question for you, is const liberating or is it restrictive, which is it? - [Audience] Both. Both, right well it depends. If you are implementing this function it's restrictive, and if you're the user of this function it's liberating. And so what happens if we turn the tables on the user and force them to be the ones that observe const. Well suddenly when they do, you know, bad things. Nobody feels like, I don't think anybody would feel too sorry for the author of this code if something bad happened as a result of him doing this const cast. Is there really any difference when you cause undefined behavior because you used a signed integer rather than an unsigned integer. Well, I don't know I've tried arguing with people and of course there's a certain point at which you just figure you try and plant a seed in somebody's head and walk away. Because sometimes it takes a long time to get people to come 'round to your way of thinking. Maybe if they're about to buy a car, and it has zero miles on the clock perhaps you could persuade them that unsigned is not the, you know, wraparound is not the best way to go about things. And here there's reasons why unsigned having defined behavior perhaps isn't such a great thing after all. Anyway, if you're arguing... - [Audience] you're losing. You're losing, so let me just show you some compiler explorer stuff. So these are some of the examples that we're, that I found on this blog and this one's probably not that surprising, well you know if you increase a signed integer it's bigger. That's not the case with unsigned here, I'm, on the left we have what the code looks like if T is a signed integer, and on the right we have what the code looks like if T is unsigned and here it's a little bit simpler. Because we know that, you know, if you add a positive number to another positive number, you get a bigger number, right? Well not the case with unsigned, so you have to do extra checks to make sure that number isn't now very, very low. Okay this one's pretty good. This is pretty extreme actually, I mean I am cherry picking some of these examples for sure. But here again, if you multiply x by, you know, a number and then you divide it by a smaller number, well you're gonna end up with something that was bigger than x to begin with and in this case, 14 divided by 7 is 2 and so there's basically something that, a hacky way to double the value. So just, wow, five minutes (beeping sound) really isn't very long, so there are just more examples like this and I recommend you go to this blog-- - [Announcer] He's overflowing