I already regularly use libraries but I always enjoy a new computerphile video even if I don't necessarily learn something new. Never be complacent, there may be a gap in your knowledge that you weren't even aware of.

Been programming for years, still watch this.

This really nicely brings linkers, static libraries, and dynamic libraries together

Elegant description of static and dynamic libraries. I wish KZfaq was around during my CS undergrad days. Or this channel.

Those classic vintage PCs in the background! Those things had personality!

Libraries are very very important. I use a lot of libraries for my code, and even abstracted a lot of recurring stuff in my own library, to link to my different small programs.

TIL this channel is the most subscribed Tech channel in GB

C can be used in environments where you just don't need "print". Like perhaps on bare-metal embedded systems. On such systems you also want your program to be tiny as well, in which case "print" just becomes superfluous.

I hope you never stop making videos. I watch a lot of KZfaq channels, but I get excited for a new Computerphile video in a completely different way than most of the rest.

I can't stop looking at that Amiga 1000 in the background.

4 years of college and 4 years of industry work, but it took one video to finally really understand what a library is trying to do. Thanks for this video, I feel a little less like a horse at the steering wheel now.

its always good to have either a review of your toolbox... or if needed nice to add a new tool to your toolbox / tool belt. =D

I want that shirt. Well, not that particular one, but one exactly like it.

Thanks for an interesting introduction to the subject. I’m an old school programmer from the 70s. Back then using libraries was pretty fraught because often they didn’t perform as specified. Now I’m retired and mostly program embedded systems for fun. Even now it’s not uncommon for a library to have faults. Even something as innocent as recompiling with a different version of a compiler can alter the way a library behaves.

very straightforward explanation, nicely done, thankyou.

Most of, if not all librarys for visual basic are written in C or C++. I started with C and when I started playing with visual basic I wrote libraries for it because I wanted to do something or didn't know it existed in VB. I found C and VB worked great together. I think the first few versions of windows the code started in Pascal. Mixing Pascal and C/CPP can be a pain because they put the arguments in function on the stack backwards. Lol . Thanks , always great videos!

I'm fond of the way that NEXT and macOS use structured .framework folders to group the headers along with the compiled libraries and other resources. It's more sensible than the old-school *nix approach of scattering the components among several folders, such as within the /usr/local folder. It's worth mentioning that dynamically-linked libraries are at the heart of all modern operating systems, and that software applications are nice and small because they only need to contain their own logic, and are linked to the system resources they need when they are loaded for execution.

Awesome, I think I finally understood what a linker does!

Compilation error. Your function must return int, but it does return nothing.

First class, as usual, from Dr. Bagley

7:50 It allows the shared library to be updated separately from your executable. For example, a newer version with newer features, bug fixes etc ... so long as it remains backward compatible, you don’t need to recompile or relink your executable to take advantage of it.

Finally after two or three decades I (partially) understand what a .dll is.

I think, #include or similar things like \input in LaTeX is the most powerful tool in computing. Splitting up files and even organizing it into subdirectories helps a lot, when you want to find a part of your code. With this you only need a simple texteditor, but today many source-code files of codebases on the internet get too large and you need an advanced IDE to find specific functions again. I personally make a file for every bigger function or structure/class definition, if it takes more than 10 lines. The "subfiles" are saved in a subdirectory with the name of the module and included by a header file with the same name. The header file also contains forward definitions before the deeper includes(C/C++), which creates an overview of all elements in the module and even can solve cyclic dependencies, which should only happen inside a module and never escape it (however you should avoid cyclic dependencies). Here is some sample code: structs.hpp ------------- #pragma once // this is the root file of the module structs namespace structs { // overview struct a; struct b; void connect(a* lhs, b* rhs); }; // implementation in some subfile depends other modules: #include #include "utilities.hpp" // subfiles #include "structs/a.hpp" #include "structs/b.hpp" #include "structs/connect.hpp" structs/a.hpp --------------- #pragma once namespace structs { struct a { b* p; }; }; structs/b.hpp --------------- #pragma once namespace structs { struct b { a* p; void foo() const; }; }; // include function definition #include "b/foo.hpp" structs/connect.hpp ----------------------- #pragma once // this submodule/function depends on the actual implementation, not only the typename, which can be used for pointers without definition -> opaque pointers #include "a.hpp" #include "b.hpp" namespace structs { void connect(a* lhs, b* rhs) { a->p = b; b->p = a; }; }; structs/b/foo.hpp --------------------- #pragma once namespace structs { void b::foo() const { std::cout

I'd love to see that BBC Master behind Dr Steve in action. Wonder if it has any upgrades, like a second processor.

These blokes are great.

So would you be able to use c all by itself, without any library? For example, if you knew the architecture of the computer very well, would you still be able to draw graphics, manipulate registers, etc, all with bareboned c?

Awsome video. I wish I watched this 25 years ago 🤔😢

Computerphile your great.

Actually printf is an interesting case, because it shows up the drawbacks of trying to do everything as a library routine within the limited type system offered by C. The trouble is that printf needs to be _polymorphic_ -- accept arguments of any mixture of different types -- which C really cannot handle. So it simply gives up and doesn’t bother checking the argument types. There is another approach, which is illustrated by the memory-allocation API in Modula-2. The language defines built-in “NEW” and “DISPOSE” routines, which are fully type-safe, because they are constructs known to the compiler. But the language itself doesn’t define any memory-allocation routines. Instead, these constructs are translated to lower-level calls to routines named “ALLOCATE” and “FREE”, which are type-unsafe, and not defined anywhere in the language. Instead, they have to be provided somewhere in the program, or imported from some library. This way you get the best of both worlds -- type-checking at the high level, but full versatility of implementation at the low level. Imagine if something similar could be done on a more general scale, for I/O and possibly for other things. C++ uses a similar idea for its memory-allocation mechanism, but unfortunately its “” I/O operators are a bit rubbish. And its printf support is just as unsafe as in C. GCC tries to do some type-checking of printf format strings. But this cannot work if the string is dynamic, since that requires the argument type information to be available at run-time.

Dynamically linked also saves disk space which used to be an issue. Not so much anymore.

3:00 Consider that the Unix kernels were themselves written in C. So a userland C program calling printf would pass control through the runtime library into the kernel, which would then do ... what? It can’t be language builtins all the way down, at some point there has to be actual reusable code to implement I/O.

y u no return int

2:49 Because then the language gets *bloody huge* . This was the approach taken with BASIC back in the days of 8-bit micros -- every vendor’s implementation had built-in commands to do screen graphics, disk file I/O, play sound, and every other feature they could think of sticking in. It just made the language too complicated.

Please add/enable subtitles.

Where does he get all that tractor-feed paper from? There’s nobody still making it, is there?

Hello does anyone know about the acorn risc os lander game did this game have sound back in 1987.thanks

Very intetesting ! Not the clearest explanation but after two views I think I understood XD Had to figure out what compiling and printf were in the story

Something I've been learning about recently is how dynamic linking isn't nearly as useful as it's purported to be. Apparently it introduces security risks, slows down program execution, causes dependency issues (.dll hell), and doesn't even save very much space. Everyone still uses it though because everyone expects it to be there

Sheer delivering Verbal Diarriaha!

I can't remember the last time I saw fanfold printer paper. Maybe the late 80s? I guess that they probably still sell it, but who uses it? And for what?

And now imagine the Code Library of Babel!

Kept staring cross-eyed at his shirt but no 3D image popped up. :(

“#include” is such a crude mechanism. Why isn’t Ada-style separation of module interfaces and module bodies more popular? Or look at Python’s module system. The nice thing about both is that they don’t pollute the global namespace without you asking them to.

Esto le puede servir a muchísima más gente. por favor agreguen los subtitulos!! aunque sea en Inglés!!!!

What would we do without libraries?

I really like the series. But it is often a little to"consumerfriendly". Wouldnt it be possible to have two versions of such a video, were one of the videos is like todays while the additional video contains more tech-savy information?

if this is how this works, why is it I can't just run windows binaries on linux, or have some translator code to convert it but it'd all be one big jumble of a file so it's not actively looking for compiled libraries? Just a question out of curiousity after hearing how the concept works.

@ 7:50 He says It doesn't even have to be the same language... How does the compiler link to pieces of code that are not the same language; how does that work?

Someone do a video on Numbers Stations!!!

Doesn't it make the program bigger than it's necessary?

Did anyone of you recognizes the computer models standing in the background? I do know them all.

Q.Can you make your own library for functions which you usually use? */I ask this because. Does fetching functions from multiple libraries make you code slower to react? instead of using one library with all the functions you have call for, in a code. _warning complete beginner!*/

I wonder how this channel has haters that dislike videos always

0:40 int function doesn't return anything

alert("I love computerphile");

Just a question.. If i write a program in a language such as python or java which does not compile the code directly into an executable file.. will all end users who utilize my program have to download a python or java compiler just to run my software?

My Windows 10 calculator has a fault; if want to rase two by the power of pi, it gives me a invalid input error message.

Please add subtitless

Where does "void" come from, BTW?

import java.IO; using system.IO;

Having started as a COBOL programmer back in 1989 and currently working as a 'full stack developer'(make what you will of that term) I am slightly concerned about all the libraries the young developers just pull in to projects willy-nilly. To show how ridiculous thing have become our UI testing framework requires a framework with 500MB of Javascript and related xml files. I think it's all a bit over the top.

What if you include a library but don't use all its functions? Do you just waste disk space?

Has Computerphile ever looked at SmallTalk?

It's annoying how hard some libraries are to get working on Windows... actually almost anything programming related seems to be an absolute pain to get working on Windows but for various reasons I still hadn't switched to Linux. I guess with VS it's not _too_ bad but I'd rather use CMake and VSC or CLion over an incredibly bloated IDE like VS.

When a library is OO is it still just code? Seems a bit inadequate to describe a library as a set of routines. That's only a fraction of the picture, surely?

I am an old-fart. One of the biggest reasons for dynamic libraries was to save space. If you had five programs that all use the same 20K IO library, you could store the library once on the disk and free up 80K, lots of space on a 360K floppy. The sport of byte counting came to an end about the same time as the 1G drives came out. Now I have 5TB on my home development server. 20K is nothing.

You can't call an int function without returning an int value. Should had been a void.. Basic stuff

import this

"printf()" is a function, not a command

The most important thing about C isn't C it's how to compile C. You have to know Makefiles and the difference between Includes and Libraries even thought the two have a one to one correspondence and you have to be able to include all the C libraries when you compile them. Getting a program just to compile is huge. Make-files are in a completely separate language from C. I think it's M4 but I'm not even sure. In 1993 I bought a public domain C compiler for the Amiga and never got it to work because I couldn't figure out how to get it to compile at the command line. Finally I bought an assembler when I went down to LA. I was able to get that to work because it had a GUI. But with compilers you pretty much still have to know how to compile at the command line because relying on a GUI just mean's at some point you aren't going to know why your program isn't compiling.

Knowledge for knowledge everything is recycled nowadays if you tech one person how to grow an apple tree tell him to pass it on to the next person and so on!

despaci

Way too shallow. As other comments show, too many programmers educated in the past 20 years don't understand the fundamentals of how actual (static) libraries work in the common model of C and C++ compilers, some are mislead by advanced "dead code removal" features of premium IDEs, some think everything should be DLLs, some don't understand the concept of DLL unloading, and some are caught in a vortex of language/vendor syntax. It's an increasing burden cleaning up their garbage, and I would have hoped that a video like this would at least have explained that libraries work on a file / compilation unit basis and will include functions that are in the same file on an all/nothing basis, but different files in the same library on an "if referenced" basis. There are more advanced engineering principles (to be taught elsewhere) that need to be applied when writing public libraries, such as API/ABI stability, unloading support, multicaller support, portability beyond ones favorite OS (be it Unix, Linux, Windows, whatever), documentation beyond data type dumps etc.

Unfortunately object-oriented programming makes code reuse far more difficult and inefficient than it needs to be.

Just don't delete a library on a blockchain... especially one which is a requirement to unlock a wallet! Parity wallet 'hack'...

C language is not the best for explaining libraries. It has the most complicated system today. Any modern language can just include and never think about all these details C language has.

Only script kiddies use libraries. Real men code everything from scratch.

booooring, "Computer for dummies". Who's the target for this generic babbling ?