Re: CString to char* conversion - C / C++ / MFC Discussion Boards

Sarath C31-May-06 20:46

31-May-06 20:46

I dont think that there is problem in type casting.
It is the operator overloaded in CString.

Sa^Rath

"D on't blindly follow rules you read somewhere without verifying that it makes sense for your situation!"

Re: CString to char* conversion [modified]

Stephen Hewitt31-May-06 20:49

Stephen Hewitt

31-May-06 20:49

You don't need an explicit cast to use CString's operator LPCTSTR. Here's an example:

CString s("Hello world!");
const char *pString = s;

You don't need a static_cast<LPCTSTR>(s) or a (LPCTSTR)s. Also note that this isn't a cast in the normal sense; it's a user defined conversion operator.

Don't use GetBuffer unless you need to make modifications.

In short here are the rules:
- If you need a const pointer do nothing: the compiler will work out what to do.
- If you need non-const pointer use GetBuffer.

Steve

Re: CString to char* conversion

Sarath C31-May-06 20:45

Sarath C

31-May-06 20:45

LPCTSTR

for get buffer, u may have to call release buffer.

if it is doing in a large source code base, and if miss a release buffer it will be hard to find and fix it.

u can modify a CString content by calling many other services provided by the same class.

Sa^Rath

"D on't blindly follow rules you read somewhere without verifying that it makes sense for your situation!"

Re: CString to char* conversion

NiceNaidu31-May-06 20:53

NiceNaidu

31-May-06 20:53

u r right Sarath,

But the problem is GetBuffer takes the parameter for length ,
So i need to call GetLength and test whether the length is greater than 0,

So, this is a big process.

if i use LPCTSTR,

it is returning const char *(void) but i when i require const char*, this is not going to help me.

Is there any alternate to these two???

Appu..
"If you judge people, you have no time to love them."

Re: CString to char* conversion

Sarath C31-May-06 22:32

Sarath C

31-May-06 22:32

Sorry for the late reply my connection got disconnected

it is possible to do in this way

its working for me.. but I donno whether it is the right way or not

CString strText("test");<br />
LPSTR lpStr = (LPSTR)(LPCSTR) strText;

Sa^Rath

"D on't blindly follow rules you read somewhere without verifying that it makes sense for your situation!"

Re: CString to char* conversion

Steve Echols31-May-06 20:47

Steve Echols

31-May-06 20:47

Depends on what you want to do with the string.

If you want to modify it, use GetBuffer or GetBufferSetLength, which returns an LPTSTR (not const). Just remember to ReleaseBuffer.

If you're not modifying the string, you can use operator LPCTSTR, since it's const.

- S
50 cups of coffee and you know it's on!

Re: CString to char* conversion

toxcct31-May-06 22:57

toxcct

31-May-06 22:57

if you want to convert to char*, use (LPSTR)
if you want to convert to TCHAR*, use (LPTSTR)
if you want to convert to const char*, use (LPCSTR)
if you want to convert to const TCHAR*, use (LPCTSTR)

use GetBuffer() if you want to perform some modifications on the string...

TOXCCT >>> GEII power

[VisualCalc 3.0 updated ][Flags Beginner's Guide new! ]

Re: CString to char* conversion

NiceNaidu31-May-06 23:11

NiceNaidu

31-May-06 23:11

U mean type casting the CString ??

CString strTest;
To convert this to const char* ,can i use (LPCSTR)strTest ??

Appu..
"If you judge people, you have no time to love them."

Re: CString to char* conversion

toxcct31-May-06 23:13

toxcct

31-May-06 23:13

NiceNaiduTo convert this to const char* ,can i use (LPCSTR)strTest ??

what i said... so, yes !!

TOXCCT >>> GEII power

[VisualCalc 3.0 updated ][Flags Beginner's Guide new! ]

Re: CString to char* conversion

Nibu babu thomas31-May-06 23:14

Nibu babu thomas

31-May-06 23:14

NiceNaidu wrote:
CString strTest;
To convert this to const char* ,can i use (LPCSTR)strTest ??

const TCHAR *pStr = strTest;//no need to typecast

Nibu thomas
A Developer

Programming tips[^] My site[^]

Re: CString to char* conversion

David Crow1-Jun-06 4:09

David Crow

1-Jun-06 4:09

NiceNaiduTo convert this to const char* ,can i use (LPCSTR)strTest ??

Yes, but the cast is unnecessary. Others have explained this.

"The largest fire starts but with the smallest spark." - David Crow

Re: CString to char* conversion

William.Wang31-May-06 23:22

William.Wang

31-May-06 23:22

neither of those two methos r correct, because both of them return LPTSTR OR LPTSTR, but they r different to char *, when UNICODE is defined beforehand, then LPTSTR equiles w_char *. so I think u should judge if the UNICODE is defined to decide how to convert to char *

life is like a box of chocolate,you never know what you r going to get.

How to use c++ header file in .c file

saravana pandy31-May-06 20:33

saravana pandy

31-May-06 20:33

Hai,
I am to use a .h file in .c file. In the .h file i have to give a definition for a c++ class. I have to use that .h file in the .c file not .cpp file. how can i use that. To say in simple words, i have to use c++ code in a c code( that too in linux) Can any one help me???
Any help appreciated

Saravana Kumar

Re: How to use c++ header file in .c file

NiceNaidu31-May-06 20:37

NiceNaidu

31-May-06 20:37

C does not support Class concept,
So replace all the Classes with structures and try.

Appu..
"If you judge people, you have no time to love them."

Re: How to use c++ header file in .c file

toxcct31-May-06 22:45

toxcct

31-May-06 22:45

bad idea... structures doesn't support visibility operators nor member functions...

TOXCCT >>> GEII power

[VisualCalc 3.0 updated ][Flags Beginner's Guide new! ]

Re: How to use c++ header file in .c file

Sarath C31-May-06 20:41

Sarath C

31-May-06 20:41

whhich compiler u r using ?

if u r using a C compiler make the class definition in

#ifdef __cplusplus

// class Definition

#endif

Sa^Rath

"D on't blindly follow rules you read somewhere without verifying that it makes sense for your situation!"

Re: How to use c++ header file in .c file

saravana pandy31-May-06 21:50

saravana pandy

31-May-06 21:50

Ya Thanks Sarath. It works i am to use cc compiler.

Saravana Kumar

Beware the C++ implicit conversion

Sarath C31-May-06 20:10

Sarath C

31-May-06 20:10

An article I found at OldNewThings

Beware the C++ Implicit Conversion[^]

Sa^Rath

"D on't blindly follow rules you read somewhere without verifying that it makes sense for your situation!"

Disable menu [modified]

Anu_Bala31-May-06 20:06

Anu_Bala

31-May-06 20:06

CMenu* menu = GetSubMenu(2);
for(int i = 0; i < menu->GetMenuItemCount(); i++)
{
EnableMenuItem(i, MF_BYPOSITION | MF_GRAYED);
}
DrawMenuBar();
I used this code to disable my second menu.But the error comes like..
'GetSubMenu' : function does not take 1 parameters
'EnableMenuItem' : function does not take 2 parameters

I think the parameters are correct,then why its coming like this.

-- modified at 2:13 Thursday 1st June, 2006
I changed the code as this..
CMenu* pMenu = AfxGetMainWnd()->GetMenu();
CMenu* Menu = pMenu->GetSubMenu(2);
for(int i = 0; i < Menu->GetMenuItemCount(); i++)
{
EnableMenuItem(i, MF_BYPOSITION | MF_GRAYED);
}
DrawMenuBar();
This time the error is come only EnableMenuItem()

Re: Disable menu

Hamid_RT31-May-06 20:14

Hamid_RT

31-May-06 20:14

CMenu m_Menu;
m_Menu.GetSubMenu(position);
------------------
GetSubMenu(hMenu,Postion);
------------------
CMenu m_Menu;
m_Menu.EnableMenuItem(i, MF_BYPOSITION | MF_GRAYED);
------------------
EnableMenuItem(hMenu,i, MF_BYPOSITION | MF_GRAYED);

whitesky

Re: Disable menu

Anu_Bala31-May-06 20:17

Anu_Bala

31-May-06 20:17

I could not understand what is hMenu..Is that handle for Menu.

Re: Disable menu

Sarath C31-May-06 20:18

Sarath C

31-May-06 20:18

HMENU is handle to point a menu.

it is used in Win32.

in MFC we are using CMenu instead.

Sa^Rath

"D on't blindly follow rules you read somewhere without verifying that it makes sense for your situation!"

Re: Disable menu

Sarath C31-May-06 20:22

Sarath C

31-May-06 20:22

there are a lot of articles and sample snippets included in MSDN. If u r using an old MSDN look at MSDN.com

Sa^Rath

"D on't blindly follow rules you read somewhere without verifying that it makes sense for your situation!"

Re: Disable menu

Hamid_RT31-May-06 20:24

Hamid_RT

31-May-06 20:24

if you use one project Win32 use
GetSubMenu(hMenu,Postion); that hMenu is one handle to menu if your project is MFC
you can use CMenu Menu; and you dont need to parameter hmenu for menu functions m_menu.GetSubMenu(pos)

whitesky

Re: Disable menu [modified]

Sarath C31-May-06 20:17

Sarath C

31-May-06 20:17

U should pass HMENU which points the parent menu.

e.g:

<br />
   // Get the main window's menu<br />
   CMenu* pMenu = pMain->GetMenu();<br />
   CMenu* pSubMenu = pMenu->GetSubMenu<br />
<br />
    pMenu->DeleteMenu(0, MF_BYPOSITION);<br />
    for(int i = 0; i < pSubMenu->GetMenuItemCount(); i++)<br />
    {<br />
        pSubMenu->EnableMenuItem(i, MF_BYPOSITION | MF_GRAYED);<br />
    }<br />
    DrawMenuBar();<br />
}<br />

I think u need to add MF_DISABLED flag, else it will just change the menu color to gray. it wont disable the menu item

Sa^Rath

"D on't blindly follow rules you read somewhere without verifying that it makes sense for your situation!"

-- modified at 2:19 Thursday 1st June, 2006

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