generate all permutations with repetition....non-recursive in C

Question

So I would like to know how to write a non-recursive function to print all permutations given an N and r where r^N gives you the total number of permutations.

Example: N = 3, r = 2, total permutations = 8

output:
000
001
010
011
100
101
110
111

This is what I tried but of course it only works for one case:

void perm_iter(int N, int nr_vals){

    int pos = N-1;
    int i,j,k;
    int P_array[N];
    for(i=0;i<N;i++){
        P_array[i] = 0;
    }
    int val_array[nr_vals];
    for(i=0;i<nr_vals;i++){
        val_array[i] = i;
    }

    do{
        for(i=0;i<N;i++){
            for(j=0;j<nr_vals;j++){
                P_array[pos-1] = val_array[j];
                for(k=0;k<nr_vals;k++){
                    P_array[pos] = val_array[k];
                    for(i=0;i<N;i++){
                        printf("%d",P_array[i]);
                    }
                    printf("\n");
                }
            }
            pos--;
        }
    }while(pos > 0);
}

Answer 1

This is an odometer function with variable radix, not really a permutation.

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

void show(int *a, int n)
{
int i;
    for(i = 0; i < n; i++)
        printf("%1d", a[i]);
    printf("\n");
}

void gen_all_numbers(int r, int n)
{
int i;
int *a;
    if(r < 2 || n < 1)          /* parameter check */
        return;
    r -= 1;                     /* r = max digit value */
    a = malloc(n * sizeof(int));
    for(i = 0; i < n; i++)      /* start with all zeroes */
        a[i] = 0;
    show(a, n);
    while(1){
        i = n - 1;
        while(a[i] < r){        /* increment last digit */
            a[i]++;
            show(a,n);
        }
        /* find next digit to increment */
        while(i >= 0 && a[i] == r)
            i--;
        if(i < 0)break;         /* return if done */
        a[i]++;
        while(++i < n)          /* zero following digits */
            a[i] = 0;
        show(a,n);
    }
    free(a);
}

int main()
{
    gen_all_numbers(2,4);
    return 0;
}