How the C++ Compiler Works 

"But we're not talking about Linking. The video about that is in the description" >Clicks "So the first stage is actually compiling, I made an entire video about that.. Link is in the video description" WARNING: Infinite Loop Detected

I've been programming for 20 years, and I actually learned something new here. Thanks!

All my .cpp files are gonna be .cherno files now

summary: Compilation is the process where we convert our plain text of the cpp files into a machine code that is readable by the CPU. It occurs in several steps. The first step is 'preprocessing', which evaluates the proprocess statements. This is followed up py tokenizing, parsing and so on, which will create an abstract data tree(?). In cpp, files have no meaning, and this is to be compared with Javascript. The cpp compiler by default treats .h, .cpp files as the way they are, but we can specifically direct the compiler to treat any random file like any other random file. Therefore, we can just make a .cherno file, and make the compiler treat it like a cpp file. //To be honest, I didn't really get what he meant here. Going over the preprocessing statements, the most common statements are #include, #define, #prgma(?) and so on. #include basically results in the computer to find the file with that name and copy and paste its content into the current file. #define is followed by 2 arguments, and will replace all of the first argument found in the text into the second argument. To see what is going on during the preprocessing stage, we can change the property of our exe file so that it preprocesses to a file, and open the .i file with an text editor. After the preprocessing stage and a series of subsequent stages(cherno didn't cover obout these stages in these video), the compiler results in an obj file. Opening this in an text editor will show hexadecimal looking numbers, which we cannot understand. So we can manipulate the property of the project, click c/c++ --> output files --> assembly output, and change the option from no listing to assembly only listing. Compiling the file after this settings will result in a .asm file being created ind the debug folder, together with the other obj files. This is the readable format of the machine code, and Cherno uses this file to demonstrate how optimization option runs our code faster by reducing redundancy. So in our properties, we can enable optimation, which also requires to change the code generation-> basic runtime check should also be set to default. Cherno makes a 'log' function that returns the message that it receives, and *for no reason*, puts it in the middle of the 'multiply' function he created. Without the optimization, we can see in the .asm file that the compiler calls for the 'log'function for no reason, which slows down the computer by adding additional line to the code. With the optimization turned on and compiling the file again, the whole line that calls for the redundant 'log' line is just gone, because the compiler decides to delete the whole section since it understands that it is unnecessary.

Trying to master C++ for five years. You are the first person that makes sense!

Dude, this series is amazing, seriously! I come with a bit of background of assembly, c++, c# and python and you explain things so well! Thank you very much for these videos :)

Been programming c++ for just under a year now, consistently. It's amazing how I still learn new things everyday, especially from you. Thanks so much, man. I appreciate it so much.

I'm super late to the party but screw it, this was hands down the best C++ video I have ever seen, full stop. It might be the best tutorial I've ever seen. Not only are you engaging and interesting to listen to, but you make the concepts really easy to understand without oversimplifying or dropping necessary information. This should be mandatory viewing for anyone learning C++. How none of this was ever covered in my entire 4 year Computer Engineering program is beyond me.

Okay man seriously your C++ tutorials are the best programming tutorials in any language I've ever coded in. It feels so good, even if it's only scratching the surface, getting a good understanding of the underlying nuts and bolts of every line of code. Thank you very much!

I'm on my 3rd year of a computer science degree and I feel like I learned more from your videos than I did in my first 2 years. Absolutely brilliant content, pacing and delivery. I started with Java and touched on other high level languages like C#. I was really weary about moving to C++ as most videos go from the absolute basics of coding so it's difficult to find what you need. This series on the other hand delivered EXACTLY what I was after. So glad I found you. Thank you!

Love the series. Please keep it up. There is a lot of unfinished cpp series on youtube. It would be a shame if this one will fall aswell.

I just started watching your series. I just want to say that I LOVE how you go into details about everything without making it boring.

Super cool to see how the C++ code gets turned into Assembly and Machine Code, and also really helpful to have a better understanding of what the compiler is actually doing!

Best C++ series ever. I'm actuallty a very experienced C programmer, and have started diving into C++ recently. These videos are just really good. Thanks for the good work!

This is a very well done explication of the c++ compiler.

I found your channel and I am thrilled. I wish I could freeze time for anything but me, my computer, my internet connection and RU-vid servers in order to just get all this information in no time.

"so instead of fixing this like a normal person" cracked me up for some reason

Playing around like this is the absolute best way to learn the internals of programming. Not merely watching videos, but actually DOING the work. Now go play!!! 😁

I've just started with operating system development at my university (TU Dortmund - Germany) and missed out this whole compilation part (preprocessing, compilation, assembling, linking). This video helped me out a lot. Thanks for that - you've earned yourself a new subscriber! Edit: The quality of your education video is also top notch! Simple, in depth, no annoying background music, good examples. Keep it up!

I'm only a few videos in and it's such a breath of fresh air to find someone who knows their topic well enough to explain it in such easy terms. Preprocessing itself has been so badly explained to me by teachers at all levels and udemy 'instructors' and then here you go and show me that it's perhaps one of the simplest things you can imagine. Thank you. Thank you for the effort you've made in creating this.

Fast and with some background music, I think it's perfect to hold one's attention. I will recommend this series!

Quite simply the best learning resource I’ve found online for any topic. Thank you keep up the good work

This is fantastic. I have been programming for a couple months now and this cleared the water for so many things I was having trouble understanding. Thank you.

I didn't find any person like you to explain in the simplest possible way. I saw an everyday video about programming for 10 years but I never find a person to explain this detail. It's absolutely easy for me because I had experience in programming but if someone new to programming with your video learns readily.

Wow, this series is fantastic. I'm making my way to patreon right now, because I don't want to this to stop.

The background music is perfect. It keeps the viewer focused. Great job dude

Dude. I'm taking a C++ class at WGU and I can't even begin to explain to you how helpful this series is. You're a boss.

Reading the comments, I am so glad you are one of the first channels I found when I started looking for cpp tutorials...

After watching this video I started to LOVE C++, Visual Studio and The Cherno's Channel!!!

Usually when I work through video courses, I'll watch them at 1.5-2 x speed. When I see the total number of hours, I also factor the speed shift in and determine how much value a course has. Anywayz...none of that applies here :D I've worked through a number of C++ courses, but I can't resist starting from scratch with this series as I've already come across more than I had previously known. While most kids got a teddy-bear as their first gift, I'm sure you were given a laptop and a copy of Programming Principles and Practice Using C++ by Bjarne Stroustrup. No wonder EA are cranking out some amazing titles. I'm sure I'm not alone in saying that I really appreciate your effort and I'll be sure to contribute when I can. Cheers!

Your understanding of c++ is very clean, and it has motivated me to watch more videos and continue where I left off trying to understand c++

Visual comparison of before and after optimization powerfully illustrates what compilation does. I appreciate this level of detail and approach to explanation.

C'mon! I believed that compiler does some magic. Feeling the same as when I realized that Santa is fake Give me my ignorance back! : ))

Absolutely loving the series so far. Great job! Will you ever cover how to compile into DLL files and then use them as references in different projects?

This is some high tier tutorial series. Please keep it up.

By far the best video I have ever seen on this topic. Clear, concise, on-topic, with a lot of enlightening examples and with some very interesting background information. Congratulation!

I did not wanted this to end for next 2 to 3 hrs ?? really !!

3:51 "Compile me like one of your .cpp files :3"

Wow, your explanation of header files was incredibly good and simple. As a beginner I kept seeing how header files were used, but not how they worked. Good job!

Dude thank you for teaching, seriously. This exact subject was so uncovered and hand wavy at my University and you ripped into it perfectly.

"I've actually made another video specifically covering linking" "Coming Soon..." God dammit. I hate being early.

Once again, thank you for these videos, Cherno, but the music is very distracting. It might not be for you, but for a beginner trying to process all this new information while following the video, it certainly is. I really do appreciate this, don't get me wrong.

Wow, I am amazed by the content provided by this channel. Really thank you very much TheChernoProject! Seriously learning more from this free video series than my C++ class in school.

Thank you for this series!!! You cover alot of stuff that has been a mystery to me....you explain C++ much more in depth than most people....you should charge for this content....your taking all the mystery out of C++ and making it look easy.

you should make compiler construction series as well. there isn't any good one out there.

I laughed my ass of when i seen that with the header files. Just copy pasta at it's finest.

THE WAY YOU PROVE THINGS (LIKE HEADER FILES ARE CPIED THERE) IS AMAZING

The amount of amazing information in this video just blew my mind. Thank You!

"C++ is text. That's it. It's just a text file." me: *having existential crysis* EDIT: this was so pleasant to listen to like a cooking instruction. You really got it down man!

You could do more than one video a week, because at this rate I will have children before finishing the series... xd

Darn, I have to say, this tut is really impressive. I like your information density and how you present said information. I just started the tut and I'm really looking forward to the rest of the videos in this playlist :D Thanks and have a good one

This is honestly the absolute best C++ video I have ever seen. Thanks you!

"I hope you learned something new". You bet.

Well in 11:28, the code is in its hexadecimal format not binary. Overall, good tutorial for C++ learners

Thank you for making this series! It’s truly great

Very in-depth tutorial and very pleasant background music

Is your last name...Bill?

11:26 this is hex decimal :D

Omg the speed of this tutorial is soo good! Thank you so much!

You explained in one video what my professor failed to explain in two weeks. Much appreciated. 👍🏻

I think I understood everything but the video was a bit too fast for my taste. I even thought I would have the video on 1.25x speed...^^

Slight constructive feedback. Blink more. You seem to have done jump cuts to make it flow better (which is great) but you also appear to not blink at all during the intro thanks to it. It's noticeable which makes it distracting (and sorta creepy). So yeah, just try to blink normally even though its weird with lights/camera and stuff.

I remember seeing this series few years ago and thinking that the channel deserves to be way more popular... And now in 2020: 335K subs, glad you've made it! :)

Very commendable job. Having concrete explanations and examples helps understanding immensely. Support this channel people to keep these videos coming!

This video had been so valuable for me... Thank you very much. What you are doing in this channel is unique.

This is perfect. I am a software developer but do not have a formal cs degree, and this series has laid a solid foundation on stuff I had no clue how worked. Thanks

Awesome video. It's simple to understand and it's actually very fun learning from you. Keep it up!

thanks man super clear! gonna watch the rest of the series. Happy I found you and subscribed!

Cherno, you are a brilliant teacher! Thank you so much. You explain things so clearly! Please keep up this great work. I only started learning C++ today. Have been a web dev for 14 years, but want to dive into game programming. Your tuts are my go-to :)

As C compiler optimizes and compiles code in to an executable. You too have compiled lot of information in to a short and precise video. You cleared lot of myths I had in my mind for this compiling process. Thanks a lot.

This is such a great video! It helps a lot to understand what’s actually going on beneath the hood when I build projects

Great video and series . It's actually amazing your conceptualization and depth !!!

I just can't help watching your videos,they're addictive.

Wow, great video, mate! I'll watch the whole series!

Dude, I have gone through so many c++ series and almost all of them are either garbage or redundant. Your series is a pure gem. It will help me to grow my embedded systems skills. Cheers!

Wow i have been working with c++ and programming languages in general for a couple years now , but gotta say these tutorials are really good easy to understand , keep the good work Mate

This has cleared so many doubts. Thanks a lot for this video.

This was such an informational video. Even though I know assembly and learned the theory of compiler design, to see this as a real example was very interesting.

Super useful stuff here. Especially knowing how to put the output into intermediate versions. Thanks a bunch!

Very informative! It makes me want to explore compiling at the lower level. Keep up the good work!

Great and concise video and I'll have to mention that the music fits very well for these types of videos :)

Really great series dude. Keep them coming..!

What to say... This is an awesome explanation. Thank you, Cherno!

Really great series, I wish this was a thing when I first started learning.

dude, this video is amazing. Congrats!

Fantastically explained. Been programming for a few years now, but never really jumped into CPP. Really good explanation of some of the things that go on when i hit that 'Build' button.

Genius! You make complex concepts really simple. Bravo!

such a good series! Thanks.

Thanks dude. I understood pretty well. Your explanations were to the point and you did a really good job.

This honestly is the best c++ series! Absolutely amazing content! 🥳🥳🥳🥳

Wonderful explanation. Very clear and understandable while still concise. Good work!

Dude I feel enlightened. Thank you! Just starting off with this and the way you tell all this excites me.... it's like discovering a new candy!!

I think that your vids are the best on RU-vid by far for almost any programming language.

This was awesome ! The best C++ season I ever watch !

Very good voice quality, very clear explanation. I learnt many new things. Thank you :)

this is what I am looking for from long back, beautiful explanation. Thanks.

Wow, Amazing video! This is the best video series I have ever seen! Nice job! Keep it going, man! ;)

As a C++ programmer I like to review things watching videos like this. You are very clear explaining. Thanks for your videos!

This is exactly what I’ve been looking for! Great explanations, you are legend

Your presentations are simply superb. I wish I worked with someone like you...