● [zl]Character checking "@" in delphi - 荔园在线 | 深圳大学学生论坛,荔园晨风BBS,深大在线网站

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发信人: oopilix (优雅的), 信区: Visual
标  题: [zl]Character checking "@" in delphi
发信站: 荔园晨风BBS站 (Sun Jun  1 23:13:33 2003), 站内信件

1:program Project2;

{$APPTYPE CONSOLE}

var
I: Integer;
Tmp: string;
begin
repeat
   ReadLn(Tmp);
   I := Pos('@', Tmp);
   if (I > 1) and (I < Length(Tmp)) then begin
     inc(I);
     while (I <= Length(Tmp)) and (Tmp[I] <> '@') do
       Inc(I);
     if (I <= Length(Tmp)) then begin
       WriteLn('The @ occurs twice in the string.');
     end
     else begin
       WriteLn('@ found only once, in the right location.');
     end;
   end
   else begin
     if (I = 0) then begin
       WriteLn('@ not in string.');
     end
     else begin
       WriteLn('@ at wrong location.');
     end;
   end;
until False;
end.

The previous code would ignore the fact that the string could end with '@@'...
And believe me, it does check for @ occuring twice in the input. First, I know
that the @ is at I. So next I go to the following character in the string and
search for a second occurance.

2:
procedure TForm1.Edit1Exit(Sender: TObject);
var
I: Integer;
Tmp: string;
begin
if (Pos('@', Edit1.Text)>0) = false
then
ShowMessage('none');
i := pos('@',edit1.text);
if i > 0 then
  if pos('@',copy(edit1.text,(succ(i)),9999)) > 0 then
  begin
    i := 2;
    if (i=2) then showmessage('2');
  end
  else
    i := 1;
    if (i=1) then showmessage('1');
end;

but the winner is Workshop_Alex. Your code popped up a consolebox, which wasn't
any good to me, so I tweaked a bit:

procedure TForm1.Edit1Exit(Sender: TObject);
var
I: Integer;
begin
I := Pos('@', Edit1.text);
  if (I > 1) and (I < Length(Edit1.text)) then begin
    inc(I);
    while (I <= Length(Edit1.text)) and (Edit1.text[I] <> '@') do
      Inc(I);
    if (I <= Length(Edit1.text)) then begin
      ShowMessage('The @ occurs twice in the string.');
    end
    else begin
      ShowMessage('@ found only once, in the right location.');
    end;
  end
  else begin
    if (I = 0) then begin
      ShowMessage('@ not in string.');
    end
    else begin
      ShowMessage('@ at wrong location.');
    end;
  end;
end;

Works on a form now. Thanks both for your help :)

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