Rand() function

Hi.
Im looking for a simpley way to pick randomly one of thease numbers:
1-2-3-4.

I have searched on google, but finds nothing but how to get a randomnumber between 0 and some stupid max-number! :confused:

Code:

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int somevariable = (rand()%4 + 1)

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rand()%X (where X is a number) gives you a number between 0 and X-1. That's why we add the +1, so you get between 1 and X.

You could have always just read the FAQ entry on the subject.

[edit]
On an aside, did you never think to just simply add one to the number, since you know it starts at zero, and you want it to start at one? I hope you don't have to ask again when you want to generate a number starting at 2. Or 3. Or again at 4...
[/edit]

Quzah.

To answer your next question.. you probably forgot to seed your random number generator.

Code:

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srand(unsigned(time( ));

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This is to be done only once.

To answer your next next question, you'll need a set of parenthesis around that unsigned, like this for it to actually work:

Code:

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srand( (unsigned) time( ) );

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Oh, and of course you'll actually have to provide a value to the time function. So you really end up with something like this:

Code:

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srand( (unsigned) time( 0 ) );

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Or, you could have just read the FAQ as I suggested, which covers srand.

Quzah.

Oh course since this is c++ you could be using the proper type of casting:

Code:

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srand( static_cast<unsigned>( time(0) ) );

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Quote:

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Originally Posted by Da-Nuka

Hi.
Im looking for a simpley way to pick randomly one of thease numbers:
1-2-3-4.

I have searched on google, but finds nothing but how to get a randomnumber between 0 and some stupid max-number! :confused:

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Then obviously you don't know what a max number is *cough* 4 is your max number for the sequent 1-2-3-4 */cough*. It's not brain surgery...and as Quzah said, the FAQ is god...

And you can't forget that time_t isn't guaranteed to be convertible to unsigned int:

Code:

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unsigned int random_seed()
{
  unsigned int seed(0);
  time_t now = time(0);
  unsigned char *p = reinterpret_cast<unsigned char *>(&now);

  for (size_t i = 0; i < sizeof now; i++)
    seed = seed * (numeric_limits<unsigned char>::max() + 2U) + p[i];

  return seed;
}

...

srand(random_seed());

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;)

Im not that noob ;)
Just lazy!

All I needed was the function name... (first post)

And I feel I gotta defend my self a little:
I wasnt talking about 4 as the max number, if I had found ways to do that, the problem had been solved.

The maxnumber I allways bumbed into was RAND_MAX.

A example:
http://www.phim.unibe.ch/comp_doc/c_...IONS/rand.html

>Just lazy!
That's a bad kind of lazy.

>I wasnt talking about 4 as the max number, if I had found ways to do that, the problem had been solved.
I don't understand. How is "get a randomnumber between 0 and some stupid max-number!" different from what you want? Unless you want a random permutation, what you've been finding is a viable solution. Give us more detail as to what you're trying to do.

Quote:

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Just lazy!

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We're not here to do work for you. We're here to help you with problems. If you know how to solve the problem and are just too lazy to do it yourself, you'll quickly find the same attitude towards helping you.