How to create functions with a variable number of arguments using stdarg.h | C Programming Tutorial
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- Опубликовано: 17 авг 2021
- An overview of how to create functions with a variable number or arguments with stdarg.h in C. Source code: github.com/portfoliocourses/c.... Check out www.portfoliocourses.com to build a portfolio that will impress employers!
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Thank you very much, very smooth and clear explanation... Definitely one of the best C tutorials on RUclips.🥇🏆
You're very welcome Mohammed! :-) I'm glad to hear that you found the explanation smooth and clear.
i agree
Hell this opens my eyes. I never noticed that printf's placeholders not only give the output-format, but also give the number of arguments to the functions.
i havent even watched up to 5minutes of the video yet but i am already get the concepts.
You are really amazing in your teaching method
I’m so glad you enjoy the teaching method! :-)
Just want to say thanks for all your very clear and informative tutorials. I stumbled upon your channel for a specific C question and now am binge watching all your C videos, they're awesome!
Wow thank you so much for the super thanks Arne, and I’m so glad to hear you’ve found the channel and are enjoying the content! :-) If you come across a topic that the channel is not covering that you think it should, please feel free to let me know with a comment.
Beautiful and clear video! Step by step and understandable.
Your videos help me make up for what's missing and build on what I've learned in class. Thanks a lot!
You’re welcome! :-D Glad to hear you enjoy the videos.
I have a team project tomorrow, where we have to create our own print function to take care of the different function specifiers. This video just helped🥺. My go-to channel for all things coding 😊
That's awesome, I'm glad to hear this video helped! :-)
thank you so much. we are all grateful that you are providing all these great lectures for free🙏🙏🙏🙏
You're very welcome Robel! :-)
very easy to flow with your teaching, love this thank you
Thank you very much Ijeoma, I'm glad to hear you enjoyed the video! :-D
thank youu so much for this video, very clear explanation and straight to the point . I'm using c++ and learn alot from this tutorial!
That’s awesome that you learned a lot from this tutorial, and you’re welcome! :-)
Found this very helpful, thank you👍🏾
I'm very glad to hear that Anita, and you're welcome! :-D
Boi, you just saved my cpool's first project.
That’s great to hear! :-)
Thank you, this was very helpful.
these videos are really helpful for a beginner like me, thanks❤
You're welcome, I'm glad to hear these videos are helping you out! :-)
Wow 🤩 this is awesome man. Nobody has ever taught me in my academics about creating a fun in C with var num of args. In fact came to know about the H file only through this video and now I because of you know the game. Much Thanks 🙏
One of my favorite videos, this one!
Thank you! :-D
Your videos are great, love them ❤
Awesome, I'm so glad to hear you're enjoying the videos! :-)
Thank you very much. I was lost about it. You helped me a lot. I like and subscribe!!!
You're welcome, and thank you for subscribing, welcome aboard! :-)
Fantastic Video!
thank you so much I searched on it for a long time and didn't understand it
but now I understand it I grateful for you
You're very welcome Safeya, I'm glad the video was helpful for you! :-)
@@PortfolioCourses 😍
My guy I cant thank you enough, this has technically saved my life
You’re very welcome Peter, I’m so glad to hear this video was helpful for you! :-)
thank you, extraordinary explanation.
You’re welcome Amir, I’m glad you enjoyed it! :-)
What an excellent explanation
Thank you! :-)
Thank you so much you are my go to guy whenever I don't understand, your videos are very helpful.
I created my own printf function but im struggling to print strings and characters. Please may you assist me if possible 🙏
To the point, thanks bro 👍
You're welcome Nikhil! 😀
still the best tutorial on this concept in RUclips as whole; KUDOS 💪
Also, i have a question, While practicing this concept I discovered I could not use more than 1 "else if" statement in writing the function. what could cause this?
Thank you Nwabueze! :-)
Wow nice video.
Now we can even attempt to use our own made format specifier, and can now determine the number of variable arguments passed using the count of appearances of '%' instead of using strlen().
I'm glad you enjoyed the video! And yes, you could use it to implement functions like printf() with format specifiers and a variable number of arguments. :-)
I love your videos
I'm really glad to hear you enjoy the videos Khumbize, and thank you very much for the positive feedback! :-)
Think i'll need some time to get this to sink in. Thanks!
You're welcome! :-) And yes it's definitely one of those things that takes time to sink in.
This is without ambiguity, so smooth
Thank you very much Adepoju! :-D
thank you so much
You're very welcome Ahmet! :-)
Fantastic video but I was almost screaming on the typo you made on stdarg.h. But again, great video.
Totally Awesome..
Thank you! :-)
Thank you so much.😊
.
..
...
You’re very welcome Saklin! :-)
Just 2 minutes and I'm into it...
I’m glad you enjoyed it! :-)
I really like your voice and step by step teaching.
Thank you! I'm glad to hear that you enjoy the teaching style. :-)
let's recode printf using the original printf function to print the result lmao
here ive recoded printf but without flags lol hope you find it intersting.
@@allnew301 did you make your own printf function? Send a link please
Lmaoooo. This guy has completely missed the point of the entire video. Trynna be funny.
I salute you from the 42 School
Thank you Evans, I salute you back from Canada! :-)
nice presentation.
Thank you Dimitrios, I'm glad you enjoyed it! :-)
Sono video eccezionali sul Linguaggio C.
Un saluto dal'Italia.
Grazie, Massimo! :-)
Great !
I’m glad you enjoyed it Youssef! :-)
Dot g, translated to Spanish, it's "punto g" which happens to be how we named the g spot, so as a bilingual my mind went "that's what she said" automatically after "that's not a dot g".
Thx for the hard laugh. And also for the tutorial btw
Hahaha oh that's funny Oscar, and you're welcome! :-)
I have been following most of your videos and i am a proud student. So far this has been the best tutorial for me on youtube.Then about creating a printf from scratch, how do i go about this?
I'm glad you're enjoying the videos Daniel! :-) I don't have a video covering how to make printf() yet. Making a full printf() implementation would actually be a lot of work and get pretty complicated. Online there are tutorials that go over 'smaller' less functional versions of printf() implementations, like this one: www.firmcodes.com/write-printf-function-c/. One day I'd like to do a "build your own printf()" video but it may need to be limited in scope otherwise it may be too long.
@@PortfolioCourses thanks for the swift reply
You're welcome! :-)
@danieltimileyin3773 Alx maybe?
@@0xRAND0M yeah
el mejor vídeo que explica las funciones variádicas. gracias!
Gracias! 🙂
is it possible to not specify the number of args?
What is the purpose of for loop when i change from 0 to 3, you didn’t use i, simultaneously va_arg takes the next number while it’s independent of (i)
The point is to repeat the action the number of times specified by num_args. Not sure how you could do this without a for loop?
thx
You’re welcome! :-)
What happened to that good old
"int main(int argc, char* argv[])"?
Did "..." replace "char* argv[]" or are both still valid?
argc and argv are different from the stdarg library. You only get to use argc and argv with main(), not with other functions you define.
5:40 what happens if you dont put va_end(args)... ? Does it not compile? or leak memory
I didn’t know the answer to be honest but this stack overflow answer looks correct: stackoverflow.com/a/587139
perfecto
I'm glad you enjoyed it! :-)
❤❤❤❤❤
Thank you! ❤️
This is an idea only: (placeholders, A1, A2, A3, A4...........A1000) I thought this could be one of implementations for voice synthesis, or music ! Where A1, A2 and so on could also take bit wise variables such as amplitude, frequency, filtering, modulation and duration from placeholders: A1 = amplitutde, frequency, filtering, modulation and duration (5 bytes for example) > so A1 could be convoluted with 0x7 + 0xA + 0x3 + 0x01 + 0xC (5 HEX compressed values) and with a rapidly progressing stream of variables and placeholders a decomposed speech can be re-constructed. It is only an idea that could work, or could not work. If there is any designer is in this channel then what do you think of this idea? Could it work? Of course we must have a very high processing speed processor and a very high memory desnsity for this to work properly. Any idea from this audiance?
how to handle struct type with va_args? For example:
struct mytype{
char *str;
int length;
};
and a function like this:
//should compare all struct mytype input and return true, if all inputs have the same size and attribute value, and false if not
bool equals_mytype(struct mytype arg_i, ...);
Did you figure it out?
Can you please make a video that designs a complete printf function that have its own formatting methond, and it does not use the existed printf function to print datas?
I've added this to my list of video ideas Nathan. :-) This would not be a very easy function to build though I don't think, printf() has many options.
@@PortfolioCourses you are right sir that what you already mentioned here is extraordinary. I just asked you to implement printf only using stdiarg since I facing a problem with that. I think many people are struggling too.
@@nathanassefa8787 Interesting, I've heard of teachers assigning this problem to students before. It's something I'm going to look into one day, I agree it could make a good video. 🙂
@@PortfolioCourses your way of teaching is really helpful even for beginners. I am looking forward to seeing your complete printf function soon. Thank you sir.
just wondering why u didn't call the video title Variadic function or even mention the term Variadic , did i get it confused or ......? i loved the video
I tried naming the video based on what people search for. I think I should add the term "variadic function" to the description though to help people find it. :-)
Can I type cast the variable arguments?
I don't see why not. :-)
So cool, we are try into education project with implementation sprintf function, this video really open my eyes, thanks a lot!
can't process char this way for some reason
Known or referred to as "variadic arguments".
Currently trying to get va_arg to collect strings parameters. How do we collect string parameters and print?
This video is all about collecting numbers and no strings. c gets tricky when it has to deal with strings, I’m tired 😪😪
Is there also a tutorial you mad in pioneers and use cases with many examples? Punters had been messing with me. I’m so frustrated
Most of the course I’m taking rn uses pointers alll the time 😪.
So instead of this:
int x = va_arg(args, int);
You would want this:
char *x = va_args(args, char *)
if you were passing in some number of strings. :-) When we pass strings to functions what we are really passing is a pointer to a char, the first char in the string.
Yes I do have a tutorial on pointers: ruclips.net/video/2GDiXG5RfNE/видео.html. :-) You might find these interesting too:
ruclips.net/video/oe2bZKjiWrg/видео.html.
ruclips.net/video/R0qIYWo8igs/видео.html
That unnecessary if statement in for loop.
Why wouldn't you just put max=first arg before the for loop ?
You could do it that way too! There would really need to be a first argument though if you do it that way.
Can you use dark mode i wanna watch this at night without burning my retinas
I'm hoping one day that RUclips adds a feature that can somehow flip videos from a light mode to a dark mode. :-) The research that I did into this came up that it largely comes down to user preference, which has a lot to do with lighting conditions. In low light conditions dark mode can be preferable for many people, where as light mode is often preferred in higher light conditions and is often higher contrast which can be good for users watching a smaller RUclips video in the corner of a screen while coding along themselves. Unfortunately for now its one of those things where I can't please everybody, but it's something I gave a lot of thought about. :-)
Kind of a crummy way of doing it... thank the Lord for variadic templates and variadic functions!
Can you just make another characters and strings instead of numbers 😪
It should look like this:
void print_all(int num_args, ...) {
char *next_string;
va_list ap;
int i;
va_start(ap, num_args);
for(i = 0; i < num_args; i++) {
next_string = va_arg(ap, char *);
printf("%s
", next_string);
}
va_end(ap);
}
and then:
print_all(4, "test 1", "test 2", "test 3", "test 4");
This works for strings but not for single char. Error was “illegal program” or something illegal, wasn’t even the usual segmentation fault.
And besides, I have to use putchar() and not printf() since I’m kind of like rebuilding/cloning the printf function
For a single char you would have "char" instead of "char *" as the argument to va_arg(). And you would store the value that's returned into a char variable, and then output it with putchar().
@@PortfolioCourses thanks man
it doesn't make any sense 😭
😂😂alx people full this comment section kai.
I don't know what this means. :-)
@@PortfolioCourses Sorry, i'm nigerian. came across your video while trying to solve a task given to me in a school am enrolled in. A friend recommended your channel. I noticed a familliar name from the program. i was trying to speak pigdin english
@@sossesam Oh I understand now haha, I'm glad that your friend recommended the channel. 🙂 Hello from Canada!
Lmao this is surprisingly very precise and clear just a little to fast for my brain 🥲. I guess I’ll just keep implementing the rewind button.
Thanks! :-)
@@PortfolioCourses I just tried your logic to apply in a function of summing up the parameters passed.
To return 0 if number of parameters is 0
Else go ahead and perform the getting and summing to the parameters.
It works fine for when the situation of 0 and the situation of correct number of parameters and inputs.
n = number of parameters
But now it’s overdoing I just tested the code by inputing n = 8 while passing only 4 other parameters. It’s still worked and started producing very weird numbers.
How do I tell it to stop or not run if the n is not equal or to the number of parameters passed.
I hope you understand me 🥺
Hmm, that's weird. argc should be set to the number of parameters, however many. You could "loop through" argv and output each parameter as a string value to help better understand what parameters you are getting. Maybe you're not getting the parameters you think you are, that may help you to debug what's going on. :-)