CODEWITHSUNDEEP
c
olibub
olibub

Reputation: 81

How to generate random numbers from range without zero

This is my function

int nepresnost_N2(int S){

    int N2, N2_1, N2_2; 
    N2_1 = -S/10;
    N2_2 = S/10;    
    N2 = rand() % (N2_2 + 1 - N2_1) + N2_1; 
    printf("%i", N2);

}

I dont know how to make conditions for (without 0). Any ideas, thanks :)

Upvotes: 2

Views: 1063

Answers (2)

Sergey Kalinichenko
Sergey Kalinichenko

Reputation: 726539

Since your range has both a negative and a positive side, going from -s to +s, you can shorten the positive part of the range by 1, then add 1 in case when the generated value is non-negative:

N2_1 = -S/10;
N2_2 = S/10-1; // Shrink by one    
N2 = rand() % (N2_2 + 1 - N2_1) + N2_1;
if (N2 >= 0) { // Correct for zero
    N2++;
}

Alternatively you could check the result for zero, and generate a new number if necessary:

int nepresnostNoZero(int S) {
    int res;
    do {
        res = nepresnost_N2(S);
    } while (res == 0);
    return res;
}

Upvotes: 5

Bathsheba
Bathsheba

Reputation: 234685

If you want drawings to be in the range [a, b] excluding zero, then generate a random number in [a, b - 1] and add 1 to it if the returned value is non-negative.

That will have superior statistical properties to sampling and rejecting 0 values.

Upvotes: 5

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