c# probability and random numbers

Question

I want to trigger an event with a probability of 25% based on a random number generated between 1 and 100 using:

int rand = random.Next(1,100);

Will the following achieve this?

if (rand<=25)
{
    // Some event...
}

---

I thought I would use a number between 1 and 100 so I can tweak the probabilities later on - e.g. adjust to 23% by using

if (rand<=23) {...}

Answer 1

The second argument of Next(int, int) is the exclusive upper bound of the desired range of results. You should therefore use this:

if (random.Next(0, 100) < 25)

or, if you must use 1-based logic,

if (random.Next(1, 101) <= 25)