C / C++ / MFC

CPallini1-Jul-08 3:08

1-Jul-08 3:08

You shouldn't.
Smile | :)

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

[My articles]

Hamid_RT1-Jul-08 20:23

Hamid_RT

1-Jul-08 20:23

vote 5 for gray man. Big Grin | :-D

CPallini1-Jul-08 21:33

1-Jul-08 21:33

I really cannot understand voting down, this time.
CLSID of an existing COM interface should NEVER change. Like the interface itself.
Anyway, thank you friend.
(BTW Why gray man?)
Smile | :)

Hamid_RT1-Jul-08 21:46

Hamid_RT

1-Jul-08 21:46

I think 1 was of a gold member because your rate is 3 if it was of a bronze member now it was 3.67(of course its my mind Smile | :)

) and thats right never changed and why gray 1=gray man and 5=red man Laugh | :laugh:

Rajesh R Subramanian3-Jul-08 22:35

Rajesh R Subramanian

3-Jul-08 22:35

My vote too, but the score didn't go way too much up as expected. Sad buggers vote down for no reason.

Nobody can give you wiser advice than yourself. - Cicero
.·´¯`·->Rajesh<-·´¯`·.
Visual C++ MVP

Stephen Hewitt1-Jul-08 14:18

Stephen Hewitt

1-Jul-08 14:18

Of course, but you haven't supplied anywhere near the amount of information for us to help. For example, what framework did you use (if any) to make the DLL?

Steve

rjkg1-Jul-08 18:50

rjkg

1-Jul-08 18:50

this is simple sdk(not MFC) com dll.

Rajesh

std::string to char*

T.RATHA KRISHNAN1-Jul-08 1:42

T.RATHA KRISHNAN

1-Jul-08 1:42

How do I convert from std::string to char* in C++?

toxcct1-Jul-08 1:53

toxcct

1-Jul-08 1:53

std::string s = "Hello World";
 
char* psz = s.c_str();

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T.RATHA KRISHNAN1-Jul-08 2:07

T.RATHA KRISHNAN

1-Jul-08 2:07

I followed the same method. But the following code:

    std::string path = dtCore::GetDeltaRootPath();
const char* exeroot = path.c_str();
strcat(path,"/");
strcat(path,"CharacterAnimation.exe");
result = system(path);
return true;

gives me the following errors:
error C2664: 'strcat' : cannot convert parameter 1 from 'std::string' to 'char *'
No user-defined-conversion operator available that can perform this conversion, or the operator cannot be called
.\GUI.cpp(195) : error C2664: 'strcat' : cannot convert parameter 1 from 'std::string' to 'char *'
No user-defined-conversion operator available that can perform this conversion, or the operator cannot be called
.\GUI.cpp(196) : error C2664: 'system' : cannot convert parameter 1 from 'std::string' to 'const char *'
No user-defined-conversion operator available that can perform this conversion, or the operator cannot be called

How do I resolve?

toxcct1-Jul-08 2:19

toxcct

1-Jul-08 2:19

why are you using path instead of exeroot you just allocated ?

it's obvious you don't read error messages, or you don't understand what you're doing...
check your code again.

std::string path = dtCore::GetDeltaRootPath();
const char* exeroot = path.c_str();
strcat(exeroot, "/");
strcat(exeroot, "CharacterAnimation.exe");
result = <font color="red">system</font>(exeroot);
return <font color="red">true</font>;

BTW, you seem not to have takenn in account my previous remarks...

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T.RATHA KRISHNAN1-Jul-08 2:25

T.RATHA KRISHNAN

1-Jul-08 2:25

Now this line shows:

char* exeroot = path.c_str();

the following error.
error C2440: 'initializing' : cannot convert from 'const char *' to 'char *'

toxcct1-Jul-08 2:43

toxcct

1-Jul-08 2:43

T.RATHA KRISHNAN wrote:
char* exeroot = path.c_str();

add const then, as std::string::c_str() returns const char*

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CPallini1-Jul-08 2:27

1-Jul-08 2:27

I think you'll get buffer overruns that way.
Smile | :)

Stephen Hewitt1-Jul-08 14:34

Stephen Hewitt

1-Jul-08 14:34

That's assuming you cast away the consts so it even compiles.

Steve

CPallini1-Jul-08 21:26

1-Jul-08 21:26

Good point indeed.
Smile | :)

Stephen Hewitt1-Jul-08 14:33

Stephen Hewitt

1-Jul-08 14:33

toxcct wrote:
const char* exeroot = path.c_str();
strcat(exeroot, "/");
strcat(exeroot, "CharacterAnimation.exe");

Bad advice. The buffer returned from c_str is const and thus can't be modified. And it's wrong to cast away the const as it's const for a reason: the buffer used by a std::string need not be contiguous memory. If this is the case calling c_str makes a temporary buffer and copies the non-contiguous memory blocks into one contiguous memory block for you. It is not required to copy the blocks back. Also your code is in serious danger of causing a buffer overrun (if you made it compile by casting away the const): how do you know how big the buffer is?

Anyway the correct way is simpler, safe, works, is portable and requires no casts:

std::string path = dtCore::GetDeltaRootPath();
path += "/CharacterAnimation.exe";
system(path.c_str());

Steve

killabyte1-Jul-08 2:20

killabyte

1-Jul-08 2:20

You are sending strcat() the wrong param type i think.

std::string path = dtCore::GetDeltaRootPath();
const char* exeroot = path.c_str();
char* StrToCat = path.c_str();

strcat(StrToCat,"/");
strcat(StrToCat,","CharacterAnimation.exe");

etc..

CPallini1-Jul-08 2:29

1-Jul-08 2:29

Buffer overrun along the horizon.
Smile | :)