Header Issues: Guards, Name Mangling, and extern 'C'

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Header files often have things in them that confuse beginning programmers. This video explains two of them — ifdef guards and extern "C" blocks.



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Welcome! I post videos that help you learn to program and become a more confident software developer. I cover beginner-to-advanced systems topics ranging from network programming, threads, processes, operating systems, embedded systems and others. My goal is to help you get under-the-hood and better understand how computers work and how you can use them to become stronger students and more capable professional developers.

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[Minty_Meeo]

6:44
_Z prefixes all Itanium mangled symbols to make it abundantly clear that the symbol name is mangled, else certain names (global variables) can be impossible to tell if mangled or not.
7 is the string length of "getmean"
Capital P is short for pointer, i is short for int, d is short for double.

[SteelHorseRider]

In your videos every aspect of C programming looks so clear and straight forward - in my C code things just segfault and dump... :D

[lean.drocalil]

Wow! It really makes me stand in awe to see how well you can explain stuff and cram this much of excellent content into one succinct and beautiful video.

Congratulations!! 👏🏻👏🏻

[samplesandtests]

besides a college course on C++ i don't think i have used function overloading. I had assumed that both C and C++ both supported it. this is the problem with taking a C++ course with out a C course or a C++ course making the assumption that the student will only use c++ and never C. thank you i learned something new today

I know it's not common, but I always indent #ifndef, #define, #endif etc. Makes the code a lot easier to read right away. I can't see why one should not indent these guards. Jacob, thank you for such great videos. :)

[samvelabrahamyan]

Two days ago I was trying to test my C code with Boost testing library, but I gave up without understanding the reason. Now everything makes sense :D Thanks

[theshaswat]

Millions and millions of thanks for such a beautiful explanation in such a short video. Never heard "Name Mangling" before.
Please keep up the good work👍👍

[Microbert]

Wow thanks alot! Stumbled about an issue on a large mixed c/c++ project at work today where the name mangling causes some errors I couldn't explain in the first place. Then a colleague told me about the name mangling and this video came in really handy!

[ahmetelhaddadi]

Unbelievably useful and EASY TO UNDERSTAND.Bit respect, sir

[renatac]

Your videos are so great! Thank you for your work!

[johnjoyce]

Excellent delivery and a great topic for C, C++ and Objective-C compilation

[birukberhanubekele]

Thank you sir, please don't stop creating good contents like this

[Mortuus]

5:57
a) The return value is NOT part of the function signature
b) "arguments" are not part of the function signature - parameters are (arguments are "instances" of parameters)

Being painfully careful about clear communication is key in CS, especially when teaching beginners

[whirvis]

6:51 This is just a guess, but I believe the __Z17 in print_person_info and the __Z7 in getmean represent the length of the original function names 😁

[joseraphaelmaglunsod]

Thanks for this video Jacob, I understand now the used of header guards. 😊

[pramoth-dev]

Wow! I read it a lot but never understand it until I found this video. Awesome. Thank you.

[mikelemon]

Well I think you are realy onto the best ways to teach programming teaching the real fundamentals you actually need to move on explaining purposes and showing why some parts necessary in a subtructive manner good job help spread this so needed teaching model!

[coenraadmulder]

Thank you very much, this is the best explanation i have seen, if you understand a concept you will never forget. Well explained. Thank you

[harishkantsoni]

Thanks for the information. Keep uploading new videos.

[starcw]

Awesome explanation! Thank you so much!