How to generate an array of random & unique integers in C?

I am creating a C-prog that requires an array of 17 integers, all being less than 18 and unique. This is what I could do until now:

int ques_arr[17];int x,y;time_t t;srand((unsigned)time(&t));for(int a=0; a<17; a++){x=rand()%18; //Assume that srand() has been declared in the program for(int aa=0; aa<17; aa++) {  if(x==ques_arr[aa])   { do{        y=0;        y=rand()%18;        }while(y==ques_arr[aa]);      x=y;       ques_arr[a]=x;    }else ques_arr[a]=x;  }}

My current algorithm is that everytime rand() generates a number, that number will be checked throughout array whether same number already exists or not, if it does, rand() keeps on generating a number until a unique number is obtained and then it is stored in the array.If such a number doesn't exist in the array, it's directly fed in to it.

As of now, numbers stored in the array are not unique.

Any help would be appreciated.