Buckys C++ Programming Tutorials - 27 - Random Number Generator

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[@andrewlozano9473]

I've been watching your C and C++ tutorials for some time now. When I don't fully understand something from my programming books, your videos are the go to videos to complement what I'm currently learning. Thank you!!

[@Scottmilton1favs]

cout

[@Scottmilton1favs]

Yeah, me too. Good video. :-)

[@saltyman7888]

std::cout

[@rohinp784]

Anonim Vere-Casper ;

[@gamingwithus_yt5109]

return 0;

[@shalinisahnimankatalia5305]

@@gamingwithus_yt5109 }

[@MrAnonymousCitizen]

I am know I am a bit late, but this also goes for anyone having the problem. In order to actually get a random number (I don't know why it defaults to 41 if you don't do this.) You must call srand() and give it a time. NULL gives you a random number, otherwise it uses system time. So in your main loop type: srand(time(NULL)); Hope I helped! :D

[@atharvdeshpande5408]

i know this is super random but its been 10 years since you commented, what did you end up doing in life lol, did you continue programming?

[@SeRbianPlayingGames]

if any of you guys want a formula for making random numbers from like 2 to 24 it goes like this(at least what i came up with): x+(rand()%(y-x+1)); x is the starting number, y is the ending number

[@JohnnyRelentless]

It's just (rand()%22)+2. You just add whatever you want you want your lowest number to be, and you subtract that number from the maximum.

[@BruceBmk]

NO seRPg is correct your method wouldn't work for bigger numbers say your Min was 1723 Max 1863 Your random numbers would run from 1723 to 1862

[@gurindersingh614]

2+(rand()%24)

[@bekiteru7015]

you rock, how did u come up with this

[@jasonjjj27]

Thank you so much for your video series, I'm in a c++ online class, so everything I have to learn i have to read from this huge complex book, watching your videos is helping so much. You speak clearly and explain the concepts behind it well. Thank you

[@thenewboston]

@BrixXSM haha i name most of my files and classes foods. mostly whatever im in the mood for when i make the file

[@ethannguyen3840]

Sitting in class for 1 hour and had no idea what the professor is teaching. Just for 9:52 watching a video and I completely understand. What a waste of paying tuitions!

[@4g0ny]

i am in a c++ class where the teacher is of little to no use and this is delivered in exactly the way i need for my brain to digest it. a massive thanks to you, and a subscription as well.

[@geml1n]

Bucky, I seriously cannot thank you enough for these videos. Our professor links all of your videos that are relevant to the lecture and I never thought I would really use them...until today. The day of the final. I am wanting to be a mortican, not a coder but I am 80% complete with my degree, so i HAVE to finish it. It is hard to push yourself to complete something you don't even need/want anymore. I could not grasp c++ anymore the way I used to. Your videos actually make sense to me and I may have a shot of passing this class again. Thank you for what you do Bucky. Sorry for all the typos. All the best, A very sleep deprived, failing college junior

[@ahmadshah751]

other youtuber: "don't forget to like, comment & Subscribe" bucky: "don't forget to add your header file"

[@BloodOrangeLover93]

Dude you just helped me pass my programming exam, this question is always at the end of the paper

[@ThatGuyNamedBender]

i love how no matter how short/long the tutorials are from bucky I always end up spending hours watching them [=

[@stucknsolve4875]

10 years old video, but best explanation

[@MikoPellas]

This video gave me that "ohhhhhhh" moment of understanding lol

[@kenosentity6455]

You've been helping me since I was 13 bro.

[@mohammad_bilal951]

opss man this video is 9 years old OMG and you are the best teacher online i ever had thank you very much SIR :)

[@grossio5564]

very MUSH WTH AND OPSS WHAT KIND OF PERSON ARE YOU

[@jackschluchter5707]

This man is a better teacher than any professor ive had

[@parcepabs1991]

I’ve watch like 8 9 videos and in 2 minutes you made a much more simpler code and did exactly what I was looking for

[@lukaskocman7546]

Even after 10 years, it helped me a lot

[@andeslam7370]

awesome video, much shorter and sweeter than those taught during lectures.

[@RedsBoneStuff]

Did you know there is computer hardware that allows you to make truly random number generators? It gives you a random value that you use as a seed. It's based on things that are scientifically random (or at least we do not understand them well enough to predict them). Various quantum phenomena are an option here. Quantum mechanics include so much randomness :P

[@LeoMadrid]

+RedsBoneStuff Are you referring to a Psyleron REG?

[@RedsBoneStuff]

Leo Madrid Not sure what they actually are :P

[@godwinmandi8761]

Print (" You Nailed It Dude, I Like The Seeding Part")

[@TonyTxT]

what the hell..!! he isn't teaching python

[@hetaeramancer]

@@TonyTxT haha

[@Foolyfish]

THANK YOU, I really needed to know the srand function :P helped out a lot :D

[@Zovioh]

Bucky, you are officially who I'm learning my programming from now. The book I got is horrible and your channel separates the topics much better, so I can easily find what I need for my program.

[@vexion15]

This was SOOOO helpful!!! :D I was getting ready to ask a question, but then you went and answered it before the video was over!

[@SeifOrabi]

Really enjoyed this tutorial Bucky. I've always had this problem in a simulation I was working on. But at least we know why now. As always, great tutorial!

[@Allyg3000]

In order to see the seconds from 1970 or whatever just type: cout

[@tranqilo6453]

This lead me down a rabbit hole of computer history, thanks

[@fifaham]

@6:31 you may use the time function then use seconds and mints and probably date, mix them together or multiply them or whatever, so to make it look like more random

[@kpippink]

Thanks for all wonderful videos Bucky. I am struggling to learn C++ for my programming class, but your videos help me a lot :D

[@onelerv1]

This is by far the best explaination of rand() I've ever seen, seriously bucky very very well done man.

[@jaidev2717]

A million second is just 12 days, Bucky.

[@adamalrefai5838]

pretty damn smart huh! -_-

[@angelhernandezvega6064]

We're living in 2020 while Bucky be living in 1970

[@ddaniel.v]

im livin 12 days past 1970 too!

[@TakingItCasual]

I want to scream my love for his tutorials but that'd make me look like some sort of fan boy, finishing his tutorials just fills me with... bliss.

[@Adraria8]

The algorithm for random number generation is pretty simple actually. It basically involves multiplying really large numbers and taking their modulus on another really large number and using that as the next seed. Look up the linear congruential algorithm. You're vids r really helpful by the way!

[@ben1996123]

if anyone is struggling with rand(), and getting the correct range of numbers, use this: x+(rand()%(y-(x-1))) gives a random number from x to y inclusive, eg: 5+(rand()%(10-(5-1))) generates a number 5, 6, 7, 8, 9 or 10.

[@realmrjangoon]

This guy is so good, I can watch the video at 2x speed, save time and understand the whwole thing

[@loading_wait]

the algorithm does not change every second. it changes at every call of srand(...)

[@m4t4m0r0s]

Best video I’ve ever seen about this topic

[@nextblain]

FUN FACT: if u generate random numbers between 1 and 365, about only 30 of em, its almost sure that u will find 2 numbers same! (its called birthday problem from probability) awesome tut bucky! :)

[@tunamay0168]

Thank you so much for saving a CS major student life

[@kevinramdass8608]

Thank you so much bucky youre a lifesaver...I appreciate your work so much

[@ammarshah2366]

Yes, I can confirm that rand() doesn't truly generates random numbers. When I first called out rand(), it printed the same 41 as yours. Btw, thanks Bucky.

[@amygonzales8343]

Ugh I finally understand how "seed" works. Bucky kicks ass!

[@hypermeero4782]

THANK YOUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUU ur explanation was direct into the point simple LEGENDARY

[@NeilRoy]

One handy feature of srand() is you can have the user provide a number for something like a level generator for a game (this is how many level generators work, where you can provide a number and it generates the same level, minecraft does this for example). You're just providing your own seed value. This can be handy, just so you know that you don't always want to use time(). Also, random number generators are not all t hat complex. I have written my own, and the reason why I wrote my own was so that if I ported my game to another computer system (different compilers use different algorithms for rand()) I had the same code for generating random numbers on all systems and so I get the same results. You may want to have the same seed so you get the same "random" set of numbers each time for a level generator, OR, you may have a game where you want the enemies to act the same way each time it is run so the player can get used to what happens in what order and they can learn to get past certain levels, so there is a certain amount of predictability. Here is the world's smallest random number generator (there are much more complex generators out that t hat produce much better, more unpredictable results, just google it). This works nicely, try it out... *unsigned long rng_seed;* *unsigned long rng(void) {* * return ((rng_seed = (rng_seed+1)*314159265L) >> 16) & 0xFFFF;* *}* Just set *rng_seed* to whatever seed value you wish (like time() or a fixed value), and then call *rng()*, using it the same way you would *rand()*.

[@meloon2879]

you are the best! Keep doing these videos plzzzzzzzzzzzzzz!!!!!!!! love the way you teach and your humour is the best!

[@yousefgamal4557]

Your video was amazing, keep up the good work. I appreciate that, man.

[@arnold9448]

You're amazing in teaching! Love it!

[@danielodette6013]

Fun fact. When I tried rand() the first time, my random number was also 41.

[@valizeth4073]

Because rand is a garbage function and should definitely not be used.

[@SuperYtc1]

@@valizeth4073 What do you think should?

[@xbz24]

Bucky u are truly a god love you fella, SIMPLE ENOUGH

[@farhatmohammadi7224]

I love you Bucky !

[@rivipersonal]

I'm at 6:50 in the video and having trouble with my code. I've done it exactly as he has (except for the srand, since if I can't get this much to work, I don't want to keep going until I can), but it keeps giving me these two error messages: "error: expected primary-expression before '(' token", and "error: expected primary-expression before '

[@rivipersonal]

***** Thank you so much! I didn't notice that's what I was doing there, it's really hard to see in the codeblocks font. I can't believe I got stumped on that. Thanks again for the help!

[@Gervisj]

Thanks Bucky. I love the way you explain everything. You're awesome dude!

[@helloworld12321]

It's 2021 you r the best❤from Bangladesh

[@tony2351992]

you are randomly amazing. love your videos man keep it UP

[@TheK00paKingdom]

//Since everyone is posting their programs: #include #include #include using namespace std; int main() { cout

[@ibiixie]

+TheKoopaKingdom I might as well do it too.... #include GLfloat light_diffuse[] = {1.0, 0.0, 0.0, 1.0}; /* Red diffuse light. */ GLfloat light_position[] = {1.0, 1.0, 1.0, 0.0}; /* Infinite light location. */ GLfloat n[6][3] = { /* Normals for the 6 faces of a cube. */ {-1.0, 0.0, 0.0}, {0.0, 1.0, 0.0}, {1.0, 0.0, 0.0}, {0.0, -1.0, 0.0}, {0.0, 0.0, 1.0}, {0.0, 0.0, -1.0} }; GLint faces[6][4] = { /* Vertex indices for the 6 faces of a cube. */ {0, 1, 2, 3}, {3, 2, 6, 7}, {7, 6, 5, 4}, {4, 5, 1, 0}, {5, 6, 2, 1}, {7, 4, 0, 3} }; GLfloat v[8][3]; /* Will be filled in with X,Y,Z vertexes. */ void drawBox(void) { int i; for (i = 0; i < 6; i++) { glBegin(GL_QUADS); glNormal3fv(&n[i][0]); glVertex3fv(&v[faces[i][0]][0]); glVertex3fv(&v[faces[i][1]][0]); glVertex3fv(&v[faces[i][2]][0]); glVertex3fv(&v[faces[i][3]][0]); glEnd(); } } void display(void) { glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); drawBox(); glutSwapBuffers(); } void init(void) { /* Setup cube vertex data. */ v[0][0] = v[1][0] = v[2][0] = v[3][0] = -1; v[4][0] = v[5][0] = v[6][0] = v[7][0] = 1; v[0][1] = v[1][1] = v[4][1] = v[5][1] = -1; v[2][1] = v[3][1] = v[6][1] = v[7][1] = 1; v[0][2] = v[3][2] = v[4][2] = v[7][2] = 1; v[1][2] = v[2][2] = v[5][2] = v[6][2] = -1; /* Enable a single OpenGL light. */ glLightfv(GL_LIGHT0, GL_DIFFUSE, light_diffuse); glLightfv(GL_LIGHT0, GL_POSITION, light_position); glEnable(GL_LIGHT0); glEnable(GL_LIGHTING); /* Use depth buffering for hidden surface elimination. */ glEnable(GL_DEPTH_TEST); /* Setup the view of the cube. */ glMatrixMode(GL_PROJECTION); gluPerspective( /* field of view in degree */ 40.0, /* aspect ratio */ 1.0, /* Z near */ 1.0, /* Z far */ 10.0); glMatrixMode(GL_MODELVIEW); gluLookAt(0.0, 0.0, 5.0, /* eye is at (0,0,5) */ 0.0, 0.0, 0.0, /* center is at (0,0,0) */ 0.0, 1.0, 0.); /* up is in positive Y direction */ /* Adjust cube position to be asthetic angle. */ glTranslatef(0.0, 0.0, -1.0); glRotatef(60, 1.0, 0.0, 0.0); glRotatef(-20, 0.0, 0.0, 1.0); } int main(int argc, char **argv) { glutInit(&argc, argv); glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH); glutCreateWindow("red 3D lighted cube"); glutDisplayFunc(display); init(); glutMainLoop(); return 0; /* ANSI C requires main to return int. */ }

[@TheK00paKingdom]

It waits for the person to press any button.

[@jammes327]

+Josh Griffith Remove the question mark below after the closing curly brace. :)

[@nitishprajapati8546]

+TheKoopaKingdom I think that ** cin.get(); ** is somewhat like ** system("pause"); ** which unfortunately now dosen't work in ANSI C++ compilers....[even clrscr(); dosen't ] However, cin.get(); too didn't work at one command. I needed to write it TWICE for it to work ONCE........ . . However, whats the algorithm or idea behind cin.get(); ....i know that cin is object of standard namespace......but get() ? How this command works.

[@valizeth4073]

1. Avoid "using namespace std" 2. Avoid "rand", use the contents from instead.

[@kfdjhnhurjnnbjhu3ip410]

no

[@Rawoonah2cool]

thanks dude,short and sweet tutorial

[@Futureblur]

Just as sweet as your profile pic :D

[@RealCoDeR]

Very good video . Waiting for Python programming ⌛

[@samirgunic]

You would need a super accurate clock and a super fast computer to predict the seed before the computer that's generating the supposedly "random" number generates that number. You would also need the source code for the program and the function definition. It's not totally impossible, but it's not something most of us would ever want or need to do anyway. So pseudo-random numbers are good enough for most of us, and for most applications. Only a quantum computer would be able to generate truly random numbers, which is one of the reason they are hyped as the definitive solution for encryption.

[@hamedalwafi8717]

I hope everyone appreciates these tutorals cause bucky u are fucking awesome ❤️❤️❤️❤️🔥🔥🔥

[@Qazqi]

If you don't call srand(), the seed is 1 by default. Therefore, every conforming implementation will give everyone the same sequence until they change the seed.

[@jhoonyk]

For more clarification on the line 11 of this video: if you use %6 (6 can be whatever number you want) is just the range you want the generated number to be. Let's say you want a range of numbers from 0 to 211, then you must use: 1+(rand()%211); If used like this: rand()%211; // would not use the last number 211 because is not included. For more clarifications, visit: www.cplusplus.com/reference/cstdlib/rand/

[@lorenzorosales2916]

Thanks!!!!!! You explanation is clear and very helpful.

[@KFilmsProduction]

Random numbers in C++ have an algorithm, like (previous random number *((x*y + z)%n * m - k)/t ...) something like that, so the result is the same for it's first run on a computer, because it's using an algorithm, which uses constants and depends on value generated before. The probability of getting any number is almost equal, so the algorithm is considered as a random number generator. We need to change something, that bucky says :)

[@Rigardoful]

If I am not mistaken , rand() is actually a recursive function. It uses the result it last generated, to generate the next. So wha t srand() actually does, is make it not take the last result, but the number provided by it, or maybe one generated after a few calculations from the number you gave in srand(). That's what I was told at my university at least, I'm in my first year in ECE department, so I am not the most reliable source :D

[@TheXRealXBrapp]

And I used the loops variable to make it generate a new number EVERY time you use the function, rather than every second.

[@hassansardar6649]

Love you sir Briliant explaination Cleared me well Thank you soo much ..

[@radnyx_games]

Yes but you would probably be using a different random, which is using different number modifications. Random isn't static, so time will only effect the random number you are generating at that time. (I'm not quite sure, but time is either updated every second or millisecond, if it's ms, then we don't have to worry, otherwise... goodluck?)

[@RyansRecording]

you explained it very well

[@nextblain]

@AlmightyMatthew no dude thats another thing, u need to use the time function that takes in systems time and plugs it in the rand function, so everytime it generates a different number :) the thing i wus talking about is universal real life thing, if u in real life picked up random numbers by hand same thing wud happen!

[@SansP3ur]

Here's an alternative random seed generator that recasts the range from 0 to 4,294,967,295, rather than − 2,147,483,648 to 2,147,483,647: srand (static_cast (time(0)));

[@blind_neighbourhoodNerd]

excellent video man Thanks so much

[@vend57]

random numbers are actually generated from the garbage values that are collected when a random variable is declared but not initialized. for instance, if you want to design a rand() function yourself, just follow this code : int main() { int a[100],i=0; while(i

[@dikukhanikar2837]

Wow... your explanation is sooo good

[@TheCareertalk]

The number that comes out of rand() is only pseudorandom, not truly random. It basically follows a little algorithm to create numbers. It looks random, but it's not quite.

[@isaacsarte2708]

how about generating random numbers without repetition using array? in c++

[@georgerotariu3221]

Really helpful and well made. Keep it up!

[@sydneyricafort4761]

i really love your videos bucky thanks a lot

[@Darku.Matteru]

very useful tutorial;) thx I needed that random generator rly bad..

[@muhammadhariskhan8204]

Best Programming Teacher

[@moharjana]

Sir You are cool and awesome :)

[@tonyfalapatt1308]

very nicely explained I don't what I can do for you but I liked and subbed and if I can I will watch more videos and like it 😀😁

[@jammes327]

Guys if you want to have the number 0 to below 6 then #include #include #include using namespace std; int main(){ srand(time(0)); for (int a=0; a

[@johnsoto7112]

why is the program only printing 21 numbers when you made the for loop 1

[@Shawn_White]

The problem with using time() is that there are only 86400 seconds in a day making it possible to calculate every seed for a 24 hour period with relative ease.

[@TheCareertalk]

The numbers aren't really random. They just seem that way because the computer uses a complicated process to generate a number that seems random to humans. You need to "seed" the random number first. Bucky talks about this in the video.

[@asafel]

love your videos!!! thank a alot!

[@aniketfuryrocks]

Computers never create a truly random number .... Nothing is random in this world

[@donlansdonlans3363]

And reality is an illusion, the universe is a hologram

[@matthewgalema8254]

Except quantum mechanics. Example: where you would find an electron around a nucleus is random and not deterministic.

[@richam27]

1: Awesome commentary along with the videos 2: i just tried out the srand "random" num generator and also generated 41!

[@hdkimo]

i NEED help i want to generate a random array of 6 numbers ex: 6-5-31-42-27-10-15 and it has to be between 1 and 49 and i want to keep the same numbers while using the console. i dont want it to generate a new number every time i go back and forth in the menus that i created in the console but i want it to change every time i open a new console. thx

[@togmeister8604]

Bucky, wouldn't that be procedural then if your using a seed? Because when you do rand() it prints same number but when you do a seed it prints same number every time you use that seed. So shouldn't this tutorial be called Random and Procedural Number Generators. When you use the seed it's a predefined value hence it's procedural.

[@oiLynXTaZeQo]

Or another number generator, it can also be used for floats. Code: // Name : Main.cpp #include #include #include using namespace std; int main() { default_random_engine RandomNumberGen(time(NULL)); // Makes each number random every time the function is called uniform_int_distribution MinMax(1, 1000); std::cout

[@nathliea]

I was trying to use this to generate a number between 1 and 100, so I put in %100 instead of %6, but every "random" result was divisible by 5. I am REALLY new to coding so I am sure I am doing something really wrong, but I did enjoy this tutorial even though I didn't understand most of it :)

[@akarshkumar1059]

cant find a better teacher than you && dont even want to. cout

[@itskiefer]

The reason everyone gets 41 is because it's random number seed (What the random number comes from.) is probably the amount of memory used and if you've done exactly what Bucky has done, it's going to be 41.

[@qzer1990]

Most enlightening tutorial in a while, thanks man. But what functions do i.e. slot machines use? Probably not a simple rand() I guess. (;

[@ankitaroy759]

Heres my random number guessing game that had different difficulty levels: #include #include using namespace std; void play(int range , int point){ int totscore = 0; int tries =0; int num; cout

[@burhanuddin959]

Nice!

[@crazystorm1361]

It takes the actual number it generates and divides it by six and give you the remainder so say.. it generated 38, the %6 would then take 38 and divide it by six but wait... 6 doesn't go into 38 evenly so it'd put as many sixes as it can into 38 and then when there is no more room for another six (when it is 36) it will show the remainder 2. (38-36=2) so then your randomly generated number is 2. Hope that helps some

[@fatimahasan3410]

how do you add those random generated numbers together?? please help !!!

[@TheDoctow]

Because srand is a function in another class. Obviously, judging from the error, it is of type void. What you should do is delete "int s =" because you can't, and shouldn't, assign a function as a variable.