Short Sorting Problem

[workisnotfun]

I am having trouble debugging my segmentation fault error in this short code!

void radixsort(unsigned long array[]){
  int arraysize = sizeof(array)/sizeof(*array);
  unsigned long move[arraysize];
  int count[256],map[256],mask,i,group=8,val,index=0; 
  while(index<4){
    for(i=0;i<arraysize;i++){
      val=array[i]>>(index*group);
      mask = val&0xff;
      count[mask]++;
    }
    for(i=1;i<256;i++){
      map[i]=map[i-1]+count[i-1];
    }
    for(i=0;i<arraysize;i++){
      val=array[i]>>(index*group);
      mask = val&0xff;
      move[map[mask]++]=array[i];
    }
    index++;
  }
  array = move;
}

[AndiPersti]

You don't initialize "count" and "map".

Bye, Andreas

[workisnotfun]

This may be a dumb question but is there an easy way to initialize without using a simple for loop and setting everything to 0?

[std10093]

int main(void)
{
    int array[5] = { 1,1,1,1,1 };

    return 0;
}

I think you see while the loops are so beloved by many (including me)

[AndiPersti]

This may be a dumb question but is there an easy way to initialize without using a simple for loop and setting everything to 0?

If you want to set every element to 0 try

int count[256] = { 0 }, map[256] = { 0 };

By default, all missing elements in an initializer list are set to 0 by the compiler.

Bye, Andreas

[workisnotfun]

Thanks for the tip, the seg fault's fixed. On another note, is there something wrong with my sorting logic or is the parameter suppose to be a pointer to an array? When I print the values of my array before and after calling this function, the values are in the same place, unmoved.

 unsigned long j[size];
  argv++;
  for(i=0;i<size;i++){
    j[i]=atoi(*argv++);
  }
radixsort(j);

[iMalc]

By default, all missing elements in an initializer list are set to 0 by the compiler.

Which is why I do the even shorter:

int count[256] = {}, map[256] = {};

Also, you need a loop to copy the item back into the array they came from.