string conversion

[David Crow]

ginjikun wrote:

is it ok to call it as shown below

Coding schemes aside, yes. If it wasn't, the compiler would surely complain.

"Normal is getting dressed in clothes that you buy for work and driving through traffic in a car that you are still paying for, in order to get to the job you need to pay for the clothes and the car and the house you leave vacant all day so you can afford to live in it." - Ellen Goodman

"To have a respect for ourselves guides our morals; to have deference for others governs our manners." - Laurence Sterne

[CPallini]

1. one is OK. 2) is bad, since it will work only on UNICODE builds. it is better:

LPTSTR str = _T("something");
func(str);

BTW: The L prefix does the magic for wide character literals, for instance

LPWSTR str = L"something"

:)

If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler. -- Alfonso the Wise, 13th Century King of Castile.
This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong. -- Iain Clarke

[Rajkumar R]

ginjikun wrote:

1. CString str="something"; func(str);

ok.

ginjikun wrote:

2. LPWSTR str="something"; <-- just a sample, not sure how to set a LPWSTR type

LPWSTR str = L"something"; LPCWSTR str = L"something";

ginjikun wrote:

func((LPCTSTR)str);

requires care. in this case if your project is unicode, it is safe.

[ginjikun]

hi Rajkumar R, what if the project is compile with _MBCS? will it still be ok? thanks

[ginjikun]

Hi, thanks for the reply! the assignment is just a sample.. however i am more concern with how FUNC is being called. you mentioned it will work only on UNICODE. what if the project is compiled with _MBCS, will FUNC((LPCTSTR)str) still work? thanks! me

[CPallini]

if you define _MBCS instead of _UNICODE then FUNC((LPCTSTR)str) expects const char * but you're passing instead a const wchar_t *. the pointer types are quite different and you're forcing the latter into the former with static cast, i.e. mistake. :)

If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler. -- Alfonso the Wise, 13th Century King of Castile.
This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong. -- Iain Clarke

[Rajkumar R]

No, it is not ok. My previous statements is still correct. func((LPCTSTR)str); requires care. in this case if your project is unicode, it is safe.

ginjikun wrote:

what if the project is compile with _MBCS? will it still be ok?

with the project settings, whenever the LPCTSTR is defined as LPCWSTR it is safe, as the str is of type LPWSTR. AFAIK, MBCS is not wide character, so passing wide character to function taking MBCS is not safe. mostly, Wide character and single character is used without any precautions simply using generic text mapping functions, but MBCS requires additional handling like (You must keep track of which bytes are lead bytes).

[Hamid Taebi]

And see The Complete Guide to C++ Strings, Part II - String Wrapper Classes[^].

[ginjikun]

Hi, thanks again. since it is an mfc project i just cast it to CString instead. func((CString)LPWSTR) i think this should be ok... ??? me

[CPallini]

ginjikun wrote:

i think this should be ok... ???

That works thanks to temporary CString object's constructor (it perforforms the conversion). :)

If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler. -- Alfonso the Wise, 13th Century King of Castile.
This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong. -- Iain Clarke