I want to make this program more quickly

I was made this program
This program makes array which each digit is different
but it takes so much time

void generateArr() {
    int randomNum;
    int sameNum = 0;
    for (int i = 0; i < arrScale; i++) {
        while (true)
        {
            sameNum = 0;
            srand((unsigned int)time(NULL));
            randomNum = rand() % 10;
            for (int j = 0; j < arrScale; j++) {
                if (numArr[j] == randomNum) {
                    sameNum = 1;
                }
            }
            if (sameNum == 0) {
                break;
            }
        }
        numArr[i] = randomNum;
    }
}

numArr and arrScale is made in front

>Solution :

You can have a separate buffer t of size 10 and whenever you draw x, set t[x] to 1. So you can evaluate t[x] == 1 to check if x is already in your array and don’t have to loop over it.

Note that your program won’t work if your array has size greater than 10.