delphi中怎样自定义函数

......
interface

uses
......
function aaa(abc: string): Boolean; // 这一句是函数声明，告诉编译器说你声明了名叫aaa的函数

im....

function aaa(abc: string): Boolean;
begin
if abc = '' then Result := True
else Result := False;
end;
// 是不是很简单呢？

var
Form1: TForm1;

implementation

{$R *.dfm}
function ss(i,ii,iii:integer):string ;
var
a,aa,aaa:string;
begin
if ((i begin
a:=inttostr(i);
a:=inttostr(ii);
a:=inttostr(iii);
result:=a;
end;

if ((i>ii)and(ii)and(iii)and(iii begin
aa:=inttostr(i);
aa:=inttostr(ii);
aa:=inttostr(iii);
result:=aa;
end;

if ((i>ii)and(i>iii)or(ii>i)and(ii>iii)or(iii>i)and(iii>ii))then
begin
aaa:=inttostr(i);
aaa:= inttostr(ii);
aaa:=inttostr(iii);
result:=aaa;
end;

end;

procedure TForm1.Button1Click(Sender: TObject);
var
i,ii,iii:integer;
begin
randomize;
i:=random(9-0);
edit1.text:=inttostr(i);
randomize;
ii:=random(9-0);
edit2.text:=inttostr(ii);
randomize;
iii:=random(9-0);
edit3.text:=inttostr(iii);
end;

procedure TForm1.Button2Click(Sender: TObject);
var
i,ii,iii:integer;

a,aa,aaa:string;
begin
i:=strtoint(edit1.text);
ii:=strtoint(edit2.text);
iii:=strtoint(edit3.text);
//edit4.text:=q;
//edit5.text:=qq;
//edit6.text:=qqq;

begin
a:=ss(i,ii,iii);

a := edit4.Text ;

aa:=ss(i,ii,iii);
aa:= edit5.Text;
aaa:=ss(i,ii,iii);
aaa:=edit6.Text ;

end;
end;
end.