Need random number, different % times

[oj4y]

I need to generate a random number, but a better chance at generating a particular one.

For example:
I would like to generate 0, 90% of the time,
and 1 10% of the time.

I know it has something to do with:

rand() % 2 and all that, but I'm stuck.

[helios]

For your particular example:
unsigned n=(rand()%10<9);

Note: rand()%10's distribution is not completely flat. Depending on RAND_MAX, the first few values are slightly more likely.

[oj4y]

Ok how about this?

I'm writing a function:

I would like to:
return 1 35% of the time
return 2 32% of the time
return 3 33% of the time.

How would I achieve this?

[z05DSL3A]

How about somthing like (rand / RAND_MAX) * 100, to get a percentage and then retun the relavant number based on that. (if num <35 return 1...)

[oj4y]

Thank you Grey Wolf.

This is off the top of my head:

	int randomPercent;

	srand( time(NULL) );

	randomPercent = ( ( rand() ) / RAND_MAX ) * 100;

	if( randomPercent <= 35  )
		return 1;
	else if( randomPercent <= 67 && randomPercent > 35  )
		return 3;
	else
		return 2;

[z05DSL3A]

You will need to do the percentage calc as a double the convert it down to int.

[oj4y]

How can I achieve that?

As a double it keeps returning 0 for randomPercent still:

	srand( time(NULL) );

	double randomPercent;

	randomPercent = ( rand() / RAND_MAX ) * 100;

	cout << randomPercent << endl;
	cout << static_cast<int>(randomPercent);

[z05DSL3A]

You need to cast rand() to double, this will then d the division as a double giving a value between 0 and 1...

[oj4y]

Got it! Thank you!