CODEWITHSUNDEEP
crandomarr
david
david

Reputation: 55

Random characters from array without repetition

I try to create a program in C that selects random characters from the array and stores them in the second array but without repetition.

Code:

int main() {
    srand(time(NULL));
    char characters[] = { 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I' };
    char array[20];
    int size = strlen(array);

    int random, random_character;

    for (int i = 0; i < 4; i++) {
        random_character = rand() % 4;
        random = characters[random_character];
        array[i] = random;
        for (int j = 0; j < 4; j++) {
            if (array[i] == array[j]) {
                array[i] = random;
            }
        }
    }

    for (int i = 0; i < 4; i++) {
        printf("%c ", array[i]);
    }
}

My output still has at least two equal characters.

Upvotes: 1

Views: 658

Answers (1)

0___________
0___________

Reputation: 67476

  1. int size = strlen(array); undefined behaviour as array is not initialized. Additionally wrong type.
  2. Your random index is wrong as you probably want to select from all characters in the characters array, not only 4 first.
  3. Your check for a duplicate is wrong.
  4. Many small issues like wrong types.
int main(void)
{
    srand ( time(NULL) );
    char characters[] = {'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I'};
    char array[20];

    int random, random_character;
    size_t j;

    for(size_t i = 0; i < 4; )
    {
        random_character= rand() % sizeof(characters);
        random = characters[random_character];
        array[i] = random;
        for(j = 0; j < i; j++)
        {
            if(array[j] == random) break;
        }
        if(j == i) 
        {
            i++;
        }
    }

    for(size_t i = 0; i < 4; i++){
        printf("%c ", array[i]);
    }
}

https://godbolt.org/z/M9b73KK4r

Upvotes: 1

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