Delphi 2007 to Delphi 2010 (String, AnsiString and more)

Posted on 2010-09-02
Last Modified: 2012-05-10

Me again =X

i like to do the things correctly and not just to silence the compiler =)

Using Delphi 2010, in a project made in Delphi 2007 a lot of bugs corrected...
Anyway, the typecast between String->PAnsiChar and back i have some doubts


function GetSomePath: String;
  Result := 'C:\MyFolder\';

WinExec(PAnsiChar(GetSomePath + 'SomeFile.exe'), SW_SHOWNORMAL);

Works but i got...
W1044 Suspicious typecast of string to PAnsiChar over PAnsiChar(GetSomePath)

To silence the compiler i can do

WinExec(PAnsiChar(AnsiString(GetSomePath) + 'SomeFile.exe'), SW_SHOWNORMAL);

But, i really don't know if its the right way... its not i think :S

Can somebody tell me the right way to TypeCast String, AnsiString, PChar, PAnsiChar with no data loss?

Best Regards,
Question by:cebasso
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
  • 3
LVL 25

Expert Comment

ID: 33585594
>> WinExec(PAnsiChar(AnsiString(GetSomePath) + 'SomeFile.exe'), SW_SHOWNORMAL);

That is what the compiler does for you when you wrote the previous code (the one with warnings)

If you cast explicitly, the advantage is that the compiler does not complain, but the code is less readable...
Matter of choice, really, but the result is exactly the same (and as you said, both work)
LVL 25

Accepted Solution

epasquier earned 500 total points
ID: 33585651
the best solution would be to create a GetSomePathA function , and call this one with WinExec.
As we said before, force the 'A' version when some API NEED Ansi

function GetSomePathA: ANSIString;
 Result := 'C:\MyFolder\'; // always ANSI (that string is a path!!)

function GetSomePathW: WideString;
 Result := GetSomePathA; // always convert here

function GetSomePath:String;
 Result := GetSomePathA; // convertion will occur only with Delphi >2009

Call :
 WinExec(PAnsiChar(GetSomePathA + 'SomeFile.exe'), SW_SHOWNORMAL);

in other places that do have to use ANSI, use the generic version :

Open in new window

LVL 25

Expert Comment

ID: 33585663
One way to be sure if some extra conversion is done somewhere is to look at CPU code. Try with the examples above, with Delphi 2007 and 2009, you will see differences between GetSomePathW and GetSomePath, which codes are almost the same.

Author Closing Comment

ID: 33585692
Ahh ok!

So the best choice is really use a A version of many func/proc's like we said before...
Thank you again!


Featured Post

Enroll in May's Course of the Month

May’s Course of the Month is now available! Experts Exchange’s Premium Members and Team Accounts have access to a complimentary course each month as part of their membership—an extra way to increase training and boost professional development.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Suggested Solutions

Title # Comments Views Activity
URL for downloading Google Chrome for Win XP 2 281
creating threads in delphi 1 202
how can i search if string exist in array ? 3 79
Problem working with dynamic array - help 2 48
This article explains how to create forms/units independent of other forms/units object names in a delphi project. Have you ever created a form for user input in a Delphi project and then had the need to have that same form in a other Delphi proj…
Introduction Raise your hands if you were as upset with FireMonkey as I was when I discovered that there was no TListview.  I use TListView in almost all of my applications I've written, and I was not going to compromise by resorting to TStringGrid…
With Secure Portal Encryption, the recipient is sent a link to their email address directing them to the email laundry delivery page. From there, the recipient will be required to enter a user name and password to enter the page. Once the recipient …

739 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question