generating 10 unique random numbers in C

Code:

---

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

int main()
{
    int i=0,j=0,n=0,a[10],flag=-1;
    for(i=0;i<10;i++)
    {
        a[i]=-1;
    }
    while(i<10)
    {
        n=rand()%10;
        for(j=0;j<10;j++)
        {
              if(n==a[j])
              {
                  flag=0;
                  break;
              }
              else
              {
                  flag=1;
              }
        }
        if(flag==1)
        {
              a[i]=n;
              i++;
          } 
    }
    for(i=0;i<10;i++)
    {
        printf("%d\n",a[i]);
    } 
}

---

when i compile and run the above code I get -1.
it should generate 10 unique random numbers between 10, but it does not...

i use gcc this is the output

Code:

---

$ gcc random.c
$ ./a.out
-1
-1
-1
-1
-1
-1
-1
-1
-1
-1

---

Of course it does. What is the value of "i" after the first for-loop?

Also, you don't need to set flag = 1 each time in the loop for(j) - set it before the loop, and remove the else-branch.

--
Mats

its really pathetic of me...

please mods lock and delete this thread...

i didnt set i to 0 before while loop

And you should seed the generator really... with srand().

It might take a while to get the 10th slot filled (random guesses, with only one answer).

Start with an array filled with 1 to 10, then use a shuffle.