C# random number problem

Question

I have this code which should generate numbers between 1 and 100:

int aux;
aux = Game1.rand.Next(101);
if (aux <= 20)
{
     Trace.WriteLine(aux);
     seeker = true;
}

The problem is i get values smaller than 20 every time. If i change 20 to 30 in the if statement, i always get numbers smaller or equal to 30. How can i overcome this isue? Thank you.

You stopped too soon. Keep increasing it until you reach 100. Next problem to fix is getting rid of the zeros. — Hans Passant
– Hans Passant, Commented Apr 10, 2011 at 0:34

Mark Cidade · Accepted Answer · 2011-04-10 00:18:37Z

3

You need to put your Trace.WriteLine(aux); before the if statement in order for it to write out any numbers above 20 (or 30, as the case may be):

int aux;
aux = Game1.rand.Next(101);
Trace.WriteLine(aux);

if (aux <= 20)
{
  seeker = true;
  //...
}

answered Apr 10, 2011 at 0:18

Mark Cidade

100k33 gold badges231 silver badges238 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Sorin Over a year ago

Thank you. your suggestion helped me find the real problem in it :)

iehrlich · Accepted Answer · 2011-04-10 00:14:27Z

1

Try something like

int aux;
aux = Game1.rand.Next(101);
Trace.WriteLine(aux);

You get values below or equal 20 simply because you have if() clause exactly saying you need values below or equal 20.

answered Apr 10, 2011 at 0:14

iehrlich

3,5884 gold badges36 silver badges43 bronze badges

5 Comments

Sorin Over a year ago

if i do that, it generates random numbers correctly, from 1 to 100. but i need that if statement. i need a 20% chance for an object to have some attributes changed...

Sorin Over a year ago

ok, i need every object of that class, to have a 20% chance for an attribute to be true. any other suggestion of how i can do that ?

iehrlich Over a year ago

Not even asking about "what class?", i think the problem is that you do the following: create various instances of the class, each having a timer, hence all the timers build roughly simultaneously. If so, they will all generate the same numbers. You should generate the RNG once and call it's interfaces from all the objects.

Sorin Over a year ago

no, i had a very simple error in there ... fixed it anyway. thank you.

Pete Over a year ago

@sorin doesnt the code you have already do that since it will only enter the if block when the number is less than or equal to 20 out of 100 (20/100) = 20%...

Collectives™ on Stack Overflow

C# random number problem

2 Answers 2

1 Comment

5 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

1 Comment

5 Comments

Your Answer

Sign up or log in

Post as a guest

Related