尝试发送电子邮件的Delphi中的PW Char和String Confusion

Question

程序返回错误，预期的PWideChar而不是字符串

procedure TForm1.Button1Click(Sender: TObject);
var
  mailtoStr, subject, body : string;
begin
mailtostr := 'mailto:theirEmail@hotmail.com';
subject := '?Subject=Email Subject';
body :=  '&Body=Email Body';
ShellExecute(Self.Handle,
             nil,
             mailtostr +
             subject+
             body,
             nil,
             nil,
             SW_NORMAL);
end;

所以我把代码改为......

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

换句话说，把它全部放在一行上，然后把剩下的程序改为......

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

但是在StringToWideCharLine上遇到运行时异常错误：S

..任何想法为什么？

Answer 1

您所要做的就是将字符串放在PChar()内以“＃cast;”＃39;它是PChar。

procedure TForm1.Button1Click(Sender: TObject);
var
  mailtoStr, subject, body: string;
begin
  mailtostr := 'mailto:theirEmail@hotmail.com';
  subject := '?Subject=Email Subject';
  body := '&Body=Email Body';
  ShellExecute(Self.Handle,
               nil,
               PChar(mailtoStr + subject + body),
               nil,
               nil,
               SW_NORMAL);
end;