Distinct random numbers between 0:1

I am new to programing and i would like a script where it gives me 4 distinct random numbers between 0:1 so i could use pythagoras and make an average value of it. After some tries i managed to create numbers between 0:1, however they are all the same value, how do i make them diferent from each other? Sorry for my bad english.

#include <stdio.h>
#include <stdlib.h>
#include <time.h>

int main() {
    int x1,x2,y1,y2,sum,pythagoras;

    //x1,x2,y1,y2 must be different values
    //sum = (x2-x1)^2 + (y2-y1)^2
    //pythagoras = sqrt(soma)

    int tempo = time(NULL);
    srand(time);
    double number = ((double) rand() * 2) / ( double ) RAND_MAX;
    printf("x1 = %.3f", number);
    printf("  x2 = %.3f", number);
    printf("  y1 = %.3f", number);
    printf("  y2 = %.3f", number);
}

thanks in advance.

My question is about: