Question

Program returns an error of, expected PWideChar instead of string

procedure TForm1.Button1Click(Sender: TObject);
var
  mailtoStr, subject, body : string;
begin
mailtostr := 'mailto:[e-mail]';
subject := '?Subject=Email Subject';
body :=  '&Body=Email Body';
ShellExecute(Self.Handle,
             nil,
             mailtostr +
             subject+
             body,
             nil,
             nil,
             SW_NORMAL);
end;

so I changed my code to …

StringToWideChar('mailto:'+MailToStr+'?Subject=' + edSubject.Text+'&Body=' + edBody.Text, MailToWideChar, Length('mailto:'+MailToStr+'?Subject=' + edSubject.Text+'&Body=' + edBody.Text));

in otherwords put it all on one line and changed the rest of the procedure to…

ShellExecute(Self.Handle,
             nil,
             MailToWideChar,
             nil,
             nil,
             SW_NORMAL);

But getting a run-time exception error at the StringToWideCharLine :S

..any idea why?

Answer 1

All you have to do is to put the string inside PChar() to ‘cast’ it to a PChar.

procedure TForm1.Button1Click(Sender: TObject);
var
  mailtoStr, subject, body: string;
begin
  mailtostr := 'mailto:[e-mail]';
  subject := '?Subject=Email Subject';
  body := '&Body=Email Body';
  ShellExecute(Self.Handle,
               nil,
               PChar(mailtoStr + subject + body),
               nil,
               nil,
               SW_NORMAL);
end;