I have seg fault in my counting sort - c

Question

Here is my code, for some reason I have to use unsigned long. The gdb tells me that I have
seg fault. Can one can help me? I could not find it by myself. The most interesting thing is that if I change the type to int from unsigned long, there is no seg fault.
Code is here:
#include <stdio.h>
int counting_Sort (unsigned long ary[], unsigned long array_size,unsigned long max){
unsigned long counting[max+1];
unsigned long j;
for(j=0;j<max+1;j++){
counting[j]=0;//initize to zero
}
unsigned long i;
for(i=0;i<array_size;i++){
counting[ary[i]]++;
}
unsigned long q;
for(q=1;q<max+1;q++){
counting[q]=counting[q-1]+counting[q];
}
for(q=0;q<max+1;q++){
counting[q]=counting[q]-1;
}
unsigned long outputAry[array_size];
unsigned long d;
for(d=(array_size-1); d>=0;d--){
outputAry[counting[ary[d]]]=ary[d];// SEG FAULT IS HERE
counting[ary[d]]--;//AND HERE
}
unsigned long m;
//for(m=0; m<array_size;m++){
// printf("%lu\n",outputAry[m]);
// }
return 0;
}
int main(){
unsigned long array[7]={2,6,4,0,1,7,9};
printf("before sorting the order is: \n");
unsigned long i;
for(i=0;i<7;i++){
printf("%lu\n",array[i]);
}
printf("after sorting, the new order is: \n");
counting_Sort(array,7,9);
getchar();
return 0;
}

Answer 1

You've found the place, just not the reason.
unsigned long d;
for(d=(array_size-1); d>=0;d--){
d is an unsigned integer, which means d>=0 is always true. The loop never ends, and that's the reason of segmentation fault.
One way is to change d to a singed type:
int d;
But if that's not what you want, change the for loop to:
for (d = 0; d <= array_size - 1; d++){