I am trying to sorting a list of numbers using radixsort. But ran into a compiler
problem that I cannot solve after multiple tries.

I have two pointers one at the back of the list and the other in front. 
base is the the number of buckets I am using for radixsort.

```
struct listnode **front,**back;
front =  malloc(sizeof(*front) * base);
back =   malloc(sizeof(*back) * base);

```

Error that I am getting is: 

```
invalid conversion from void* to listnode**[-fpermissive]

```

Thanks in advance for the help.