Removing elements from dynamic arrays?

[Bill Baxter]

David Medlock wrote:

> For giggles I posted the conditional version(also public domain):
> 
> // remove items based on a predicate. returns number of items removed
> template drop_if(T)
> {
>   int drop_if( T[] arr, bool delegate(T)pred )
>   {
>     int count = 0, dest=0;
>     foreach( int index, T val ; arr )
>     {
>       if ( pred(val) ) { count++; continue; }
>       if ( dest !=index ) arr[index] = dest;
>       dest++;
>     }
>     return count;
>   }
> }
> 

And here's the range-dropping version:

template drop_range(T)
{
   void drop_range( inout T[] arr, int start, int end )
   {
     debug if ( start>=arr.length && end > arr.length)
         throw new Exception(format("Attempt to drop range %s,%s from 
size %s",start,end,arr.length));
     if (start>=end) return;
     size_t len = end-start;
     size_t max = arr.length-len;
     for (; start < max; start++ ) arr[start]=arr[start+len];
     arr.length= max;
   }
}