Delphi Pascal Source Code - Selection Sort

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Using Selection Sort to sort a Tstrings type using the 'Exchange' method...

Using Selection sort to arrange the elements in an OpenDialog.Files Tstrings element...

procedure TForm1.OpenDialogSortfiles;
var counter,  look:integer;   temp:Tstrings;
begin
if OpenDialog1.Files.Count<>1 then begin  
     temp := TStringList.Create;

         {strings with mixed upper and lower case names will not sort alphabetically
         since strings are sorted based on the digital value of letters and not the
         letters themselves...therefore the sort will be based upon lowercase strings
         but the filenames themselves will not be changed to avoid the possiblity
         of error messages on systems set to be case sensitive ... The OpenDialog Tstrings 
	property is Read Only so in order for the sort to work correctly a temporary Tstrings
	variable will be used to hold the actual indexing value for the sort}


     for counter:=0 to OpenDialog1.Files.Count-1 do
          temp.Append(LowerCase(OpenDialog1.Files.Strings[counter]));

     for counter:=0 to temp.Count-1 do 
	
	{place the smallest element in the first position, move to the second position,
	and place the next smallest element in the second position, etc}

             for look:=counter+1 to temp.Count-1 do
                 if temp[look]<temp[counter] then begin
                    OpenDialog1.Files.Exchange(look, counter);
                    temp.Exchange(look,counter);
                 end;
         

     temp.Free;
end; {if}
end;



Using Selection Sort to sort an array 

In the following example I am assuming that the array is a 'global variable' ... pass the value of the last element in the array as the variable 'Top'  ... if the array is a string the lowercase strings will be sorted before the upper case strings are sorted since strings are sorted based on digital ('ASCII') values, not alphabetical values... the 'Exchange' method for TStrings is replaced by code that does the same thing ...


Procedure TForm1.SelectionSortArray(Top:integer);

var 
counter, min, look:integer; 
temp:string;  {if the array is of integer type then temp must be defined as 'integer' etc.}

begin
        for counter:=0 to Top do begin
             min:=counter; 
             for look:=counter+1 to top do
                 if TheArray[look]<TheArray[min] then min:=look;
             temp:=TheArray[min]; TheArray[min]:=TheArray[counter];
             TheArray[count]:=temp;       
                 
         end;

end;