Delphi – Best way to sort an array

arraysdelphisorting

Say I have an array of records which I want to sort based on one of the fields in the record. What's the best way to achieve this?

TExample = record
  SortOrder : integer;
  SomethingElse : string;
end;

var SomeVar : array of TExample;

Best Solution

You can add pointers to the elements of the array to a TList, then call TList.Sort with a comparison function, and finally create a new array and copy the values out of the TList in the desired order.

However, if you're using the next version, D2009, there is a new collections library which can sort arrays. It takes an optional IComparer<TExample> implementation for custom sorting orders. Here it is in action for your specific case:

TArray.Sort<TExample>(SomeVar , TDelegatedComparer<TExample>.Construct(
  function(const Left, Right: TExample): Integer
  begin
    Result := TComparer<Integer>.Default.Compare(Left.SortOrder, Right.SortOrder);
  end));
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