Random array generation with no duplicates

I am trying to create something that generates a random array with no duplicate values. I've already looked at other answers but none seem to help me understand. I cannot think of a way to actually generate random numbers that contain no duplicates. Here is what I have tried so far:

srand(time(NULL));
int numbers [4];

for (int x=0; x!=4;x++)
{
    numbers[x] = 1 + (rand() % 4) ;
    printf("%d ", numbers[x]);
}