Using any exceptions to trigger code in Delphi - delphi

Question

Hi I am new to using Delphi and am trying to write an application that will check to see if a website is up or if there is any thing wrong with it. I am using Indy's IdHTT. The problem is that it will catch any protocol errors but not things like socket errors.
procedure TWebSiteStatus.Button1Click(Sender: TObject);
var
http : TIdHTTP;
url : string;
code : integer;
begin
url := 'http://www.'+Edit1.Text;
http := TIdHTTP.Create(nil);
try
try
http.Head(url);
code := http.ResponseCode;
except
on E: EIdHTTPProtocolException do
code := http.ResponseCode;
end;
ShowMessage(IntToStr(code));
if code <> 200 then
begin
Edit2.Text:='Something is wrong with the website';
down;
end;
finally
http.Free();
end;
end;
I am basically trying to catch any thing that is not that the website is ok so I can call another form that will setup an email to tell me that the site is down.
update: First you are right I did miss that 'then' sorry about that was removing other code and it got deleted by mistake. I did not know the specific to general when dealing with exceptions thank you. Finally I did find what i was looking for was this code here
on E: EIdSocketError do
using the uses IdStack

Answer 1

Change your code to either catch all exceptions, or add more specific ones as well:
url := 'http://www.'+Edit1.Text;
http := TIdHTTP.Create(nil);
try
try
http.Head(url);
code := http.ResponseCode;
except
on E: EIdHTTPProtocolException do
begin
code := http.ResponseCode;
ShowMessage(IntToStr(code));
if code <> 200
begin
Edit2.Text:='Something is wrong with the website';
down;
end;
end;
// Other specific Indy (EId*) exceptions if wanted
on E: Exception do
begin
ShowMessage(E.Message);
end;
end; // Added missing end here.
finally
http.Free();
end;
Note that if you're going to handle multiple exception types, it's important to go from most specific to least specific. In other words, if you put less specific (more general types) exceptions first, this is what happens:
try
DoSomethingThatCanRaiseAnException();
except
on E: Exception do
ShowMessage('This one fires always (covers all exceptions)');
on E: EConvertError do
ShowMessage('This one will never happen - never gets this far');
end;
This one will work properly, because it's more specific to less specific. Properly, it would be reversed:
try
DoSomethingThatCanRaiseAnException();
except
on E: EConvertError do
ShowMessage('This one gets all EConvertError exceptions');
on E: Exception do
ShowMessage('This one catches all types except EConvertError');
end;