[Day 16] - Static and Dynamic Libraries (ar, objdump, ld, ldd) - Crash Course in C Programming

[@timesink6325]

As a beginner to c, this is my sum up.Hope to help someone like me:) 1.complie multiple c files under the src directory: gcc ./src/main.c ./src/mymath.c ./src/mymath2.c -I./include -o prog -> prog 2.complie all c files under the src directory: gcc ./src/*.c -I./include -o prog -> prog 3.creat static library: gcc -c ./src/main.c -I./include -> main.o 4.using the archive tool: ar rcs mymath.a mymath.o mymath2.o -> mymath.a 5.embed the static library into the final executable: gcc main.o mymath.o mymath2.o -o prog -> prog 6.creat dynamic library(shared library) : gcc -fPIC -shared ./src/mymath.c -I./include -o libmymath.so -> libmymath.so 7.linked with the dynamic library : gcc ./src/main.c -I./include -o hello -lmymath -lmymath2 -L./ -> hello 8.run the hello program: LD_LIBRARY_PATH="./" ./hello 9.the difference between static library and dynamic library: the code of the static library gets embeded into the final executable at compile time, but the code of the dynamic library does not get embeded into the executable.instead, the linking happens at runtime, this requires the dynamic library to be present on the system at runtime.

[@MikeShah]

Looks like a nice summary -- well done! (Will pin for a bit)

[@timesink6325]

@@MikeShahThanks mike! i enjoy your lessons very much.

[@MikeShah]

@@timesink6325 cheers!

[@richardkombo5537]

The fact that you experience the errors and solve them make the lesson worthwhile so we are able to watch out for the same errors in the future......Your lessons are really appreciated

[@MikeShah]

Cheers, thank you for the kind words :)

[@Southpaw101]

This is exactly what I was looking for. Whole day I have been working on the c++ series and luckily found this. Thanks.

[@MikeShah]

Cheers! Happy to help!

[@dd-iu6iy]

Great lecture, you gradually move from beginner to advanced level concepts. Great teaching skills sir.

[@MikeShah]

Thank you for the kind words!

[@MichaelOzoro]

Wow! Thanks Mike (my namesake) This is really nice, I enjoyed the lesson, I like the way you simplify and break down the compilation process, thumb up to you!!!

[@MikeShah]

Cheers!

[@behrampatel4872]

Such a fantastic tutorial on fundamentals. I'm learning openCV using c++ and need to brush up on my basics (because of all the header & lib includes to get started). This video is just perfect. Hope you do windows as well. Cheers, b

[@MikeShah]

@@behrampatel4872 cheers!

[@behrampatel4872]

@@MikeShah I have one request mike. I'm trying to emulate this on windows visual studio using the developer command prompt. I'm able to get a basic hello world compiled but when I follow your tutorial on including other directories it gives me linker errors. KZbin only shows the beginning step of getting a hello world working and nothing beyond that. Can you point to a tutorial on how to go beyond that using the Developer command prompt please ? I'm resisting the urge to download gcc and follow along and call it a day. Thanks a ton.

[@MikeShah]

@@behrampatel4872 Many folks use VSCode which has a command prompt (usually folks do use gcc or mingw (windows port of gcc) to achieve this). I believe Visual Studio has the ability to run msvc in a prompt somewhere, I just have not used it (i.e. when I use Visual Studio, I use the full IDE and just hit F5 or the build&run buttons from the GUI)

[@behrampatel4872]

​@@MikeShah No probs. Its called the Developer Command Prompt. There is documentation on it on the windows website but it's written for people already in the know or to intentionally turn people off :P. I'm going with g++ and getting in some practice based on the exercises above. Happy to report that things work like a charm. I'm not able to replicate the shared object workflow on windows though. Im guessing because windows would require DLL'S instead of SO's. So the hunt begins on how to do that using g++. Cheers and you're the best... b

[@antenehtaye4973]

Thank you Mike, its a great demo hope you can pace down a lil bit i found it hard to keep up.😊

[@MikeShah]

Cheers!

[@felipealemanha]

Hey, man! Your contents is helping me a lot. Hugs from Brazil!

[@MikeShah]

Cheers! Happy to hear that!

[@rzwnhmd]

this topic was just amazing. Now I know what its meant when they say that "GCC" does some magic into compiling process. Looking forward to learn more about this topic

[@MikeShah]

Cheers, thank you for the kind words!

[@Kirfx]

Thank you so much!

[@MikeShah]

Cheers!

[@joshbrice5678]

Thank you Mike. 😄

[@MikeShah]

You are most welcome Brice!

[@michaeljumah6960]

thanks so much....this is a lifesaver

[@MikeShah]

Cheers!

[@ugochukwuokpoko7593]

Awesome piece. Can one get the "tree" source file you used during the lecture?

[@MikeShah]

Cheers! tree is installed with 'sudo apt-get install tree'

[@blaisofotso3439]

Hallo Mike, Thumb up for the videos and this topic. I will wash it later.

[@MikeShah]

Cheers Blaiso!

[@GaryChike]

The video does need sanitizing 😅

[@tsarprince]

Damn so informative!

[@MikeShah]

Cheers, happy to hear that!

[@aghiadalzein3069]

Thanks ,but this lesson was the hardest for me.

[@MikeShah]

Cheers -- there's quite a bit of new material here indeed!

[@Random-sm5gi]

Can you please talk about dlopen u mentioned at the end of the lesson? Thank you so much bro it was very helpful.

[@MikeShah]

In the planning stages -- probably have something out in the next month or two on dlopen if not sooner.

[@MuhammetUçan-y7c]

Hi, I'd like to ask a question if you dont mind. When you wrote mymath.c you included mymath.h header to it, but when I tried It actually perfectly work without including mymath.h to mymath.c file. I guess we don't need to add that but since you added I wonder if there is a special reason for that.

[@MikeShah]

Functions also provide the declaration with the definition. However, when you need to use the file more than once it could cause problems in compilation if you don't have the header

[@MuhammetUçan-y7c]

@@MikeShah Thank you for your answer.