Generate Random Number from specific integers

Question

I want to generate random number from specific integers example : generate random number from these values {2,7,9,8,11,13,16} the generated number is one of these values

Just generate random index. Look at `` facilities. – Jarod42 Dec 19 '15 at 23:31 — Jarod42, Dec 19 '15 at 23:31

score 0 · Answer 1 · answered Dec 19 '15 at 23:31

0

The simple way is: put these values into a vector, generate a number between 0 and vector.size() using rand() and use this value as index.

answered Dec 19 '15 at 23:31

Ctx

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Never use `rand()`, forget about it forever. – vladon Dec 19 '15 at 23:34
http://channel9.msdn.com/Events/GoingNative/2013/rand-Considered-Harmful – vladon Dec 19 '15 at 23:36
"between 0 and vector.size()" And what happens if you will get `vector.size()` and use it as index?.. – vladon Dec 19 '15 at 23:37
Ok. But your answer in words contains TWO horrible errors. So, your answer is incorrect. Twice. – vladon Dec 19 '15 at 23:40
Correct answer is in first comment to the question by Jarod42 – vladon Dec 19 '15 at 23:41
Using rand() is not an error, despite what you say. And I think it is quite clear what is meant with _between_. Have a nice day. – Ctx Dec 19 '15 at 23:43
Ctx, if "between" means "not including", then you again not right, you miss index 0. In any meaning your answer is not good. – vladon Dec 19 '15 at 23:46
And never use `rand()`. – vladon Dec 19 '15 at 23:47
Thank you very much for your answer i will try it @vladon – mahmoud ismail Dec 19 '15 at 23:54

Rudolf Manusachi · Accepted Answer · 2015-12-20T00:04:03.610

0

Try somethig like this:

#include <iostream>
#include <stdlib.h>
#include <time.h>

int main ()
{
  srand ( time(NULL) ); //initialize the random seed

  const int SIZE = 7;
  const int arrayNum[SIZE] = {2,7,9,8,11,13,16};
  int RandIndex = rand() % SIZE; //generates a random number between 0 and 6
  std::cout << arrayNum[RandIndex];
}

Hope it helps =)

edited Dec 20 '15 at 00:04

answered Dec 19 '15 at 23:33

Rudolf Manusachi

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Thank you but its generate the same value every time If i want to used it in a loop ;) – mahmoud ismail Dec 19 '15 at 23:55
are you sure that as index you used new `rand() % SIZE` each time? `for(int i=0; i<10; i++)cout< – Rudolf Manusachi Dec 20 '15 at 00:08
@RudolfManusadzhyan `rand()` can generate identical numbers on each start. Common fix is call `rand()` several times after `srand`: `rand(); rand(); rand();`. You can even google it - it is used very often. That's why programmers MUST NOT use `rand()`, because it is a kind of shit. – vladon Dec 21 '15 at 11:57

Generate Random Number from specific integers

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