[siriusmd99]

0,1 will do the thing for equal cantities. But you have 9 numbers and then 3 numbers. So the division is 9/3=3 (times)
Maybe you can do:

random_num(0,3) ? random_num(1, 9):random_num(12,14)

So if you have 0 it will generate number between 12 and 14 and if you have 1,2,3 it will generate numbers between 1 and 9

But I'm not sure 100%, it's just an idea.
Anyway I suggest you to do loop and repeat it until you get number different from 10 and 11.
Infinite loop can happen only if your excluded numbers are more than wanted ones. In this case you only exclude two numbers, so the probability that it will return 10 and 11 forever is just funny to think about.

Also when you add for example +1 when it's 11 it will increase the probability of number 12 by two times.
One time will be natural 12 and another time will be artificial 12 (11+1). And same for 10-1.

like this:
1,2,3,4,5,6,7,8,9,10-1,11+1,12,13,14
=>
1,2,3,4,5,6,7,8,9,9,12,12,13,14

I don't think this array looks right.

[Depresie]

There are more ways to "hack" this particular case.. but none of them would be more efficient than the method posted by fysiks..

Also it is the only method posted that doesn't screw the probabilities..

[aron9forever]

Originally Posted by Depresie There are more ways to "hack" this particular case.. but none of them would be more efficient than the method posted by fysiks.. Also it is the only method posted that doesn't screw the probabilities..

PRoSToTeM@'s method also works fine but only allows for skipping intervals of numbers
I assumed the OP gave a specific example but will probably need it for multiple scenarios
if you need to skip 10 and 12 but not 11 then you can't use that


also fysiks way is correct and probably the method used by games in time critical areas (such as chance based effects like critical damage, on every hit or shot) but needs to be hardcoded carefully


I stand by my version, not because of its efficiency, but because it's accessible and can accommodate many scenarios
Don't forget this is amxmodx help section, not C optimization discususion. Not saying these things shouldn't be explained so the users understand what is appropriate where but it's not the right topic











Should've started with this question first:
OP, what are you trying to achieve?

[Natsheh]

Originally Posted by fysiks This still skews the probabilities.

No it wont since all has a half chance to be chosen.

[klippy]

Originally Posted by Natsheh No it wont since all has a half chance to be chosen.

It wouldn't if your two intervals had the same number of elements.

[Airkish]

Originally Posted by aron9forever Should've started with this question first: OP, what are you trying to achieve?

There's 14 skin cases.
Every player have a chance to receive any of these cases when kills enemy, except 2 of them (10, 11) which are only obtainable by completing missions.

So I need to make those 2 to not be included in kill drops.

P.S. I can't just make those 2 cases 13, 14.

[aron9forever]

Originally Posted by Airkish There's 14 skin cases. Every player have a chance to receive any of these cases when kills enemy, except 2 of them (10, 11) which are only obtainable by completing missions. So I need to make those 2 to not be included in kill drops. P.S. I can't just make those 2 cases 13, 14.

so
- you will use the function quite often (on every kill)
- you probably won't be changing the cases that often
- you need this thing to be fair, otherwise as time goes by people will start racking up cases that drop more often
- you might need the flexibility to exclude other cases, maybe number 18, at some point in the future

based on this I would recommend fysiks' solution, store all the cases you want to be able to randomly select in an array, then randomly select one element of that array

it will look pretty ugly but you only need to do it once and you can do it at the top of the plugin, just make sure to add comments so you or other possible future developers know what is happening there. You don't want to look at the code again in 6 months and think "wtf was I doing here?"

[PRoSToTeM@]

Originally Posted by siriusmd99 Infinite loop can happen only if your excluded numbers are more than wanted ones.

It also can happen if random function is a constant xD.

Originally Posted by aron9forever I assumed the OP gave a specific example but will probably need it for multiple scenarios if you need to skip 10 and 12 but not 11 then you can't use that

You can just uncomment the commented block and change 11 to 12:

new num = random_num(1, 14 - 2);
if (num >= 10) {
    ++num;

    if (num >= 12) {
        ++num;
    }
}

[fysiks]

Originally Posted by siriusmd99 Infinite loop can happen only if your excluded numbers are more than wanted ones.

That is not true. With true randomness, it is still possible to always get one of the excluded numbers. However, it's extremely unlikely which is why it usually doesn't cause significant issues. The most important part of this is that you will never know how many times your while loop will execute which is just bad code.

Originally Posted by Natsheh No it wont since all has a half chance to be chosen.

No. The probabilities are skewed. The probability of getting a number from 1 to 9 is 5.555% (0.5 * 1/9) and the probability of getting a number from 12 to 14 is 16.666% (0.5 * 1/3).

Originally Posted by PRoSToTeM@ You can just uncomment the commented block and change 11 to 12: new num = random_num(1, 14 - 2); if (num >= 10) {     ++num;     if (num >= 12) {         ++num;     } }

So, what if you need to exclude 3, 8, 9, 15, 21, and 26? (Rhetorical Question) It's not scalable code. So, if you go with a more scalable solution now, then you wont' have to rewrite the [functional part of the] code in the future when you add more exclusions.

[KiLLeR.]

Originally Posted by fysiks you will never know how many times your while loop will execute which is just bad code.

I thought that the idea for 'while loops' are to use em, when you don't know how many times they gonna be executed?!?