Simple as hell

[Ran]

Hello.

Here is a very simple question. My function is defined as:
char * myfunc (void);

My function prepares some text and want to pass it. I would like at first to send the whole text, so I have the possibilites:
1. static char szText [1000] and then return the pointer.
2. define char szText [1000] globally.
3. use CString object.

I wouldn't like to use CString and I guess there is some trick programs use in this case. The best solution I have in the list is to use static, but I don't want it to take the memory forever. I don't want to use calloc in one function and free in another as well.

OR use new ro malloc to create a new buffer and make sure that the calling function deletes it when finished. Not generally considered a good practice but it works. I don't know why you don't want to use CSting though...they are very simple to use and reasonably efficient (not great but O.K.).

Use CString

It would be easiest to pass a CString object to:

void myfunc (CString sMyString) // sMyString may grow in size with no problem

Next place the following code fragment in the calling function:

CString sMyString;
myfunc(sMyString); // May cast sMyString into LPTSTR if you want. Read document

CString object is often more convenient than char *. It will be destroyed automatically as it goes out of scope.

[Torkel]

void myfunc (const CString& InString)
{

// do processing here

return OutString;
}

[Masaaki]

Hi, Sally and Sue.

Your code is wrong.

void myfunc (const CString& InString)
{
// do processing here
return OutString;
}

1) If you want to return CString,
CString myfunc(CStrig str)
{
......
return OutString;
}

Or use reference.
void myfunc(CString& InString)
{
CString str("Aha");
InString += str;
}
//In this case, InString is updated without return.
That is,
CString str("First ");
object.myfunc(str);
//now str is "First Aha"

If I have some errors, please point it out.
Regards.
-Masaaki Onishi-

[Torkel]

CString myfunc(const CString& inString)
{
CString outString;
// do processing here
// like outString = inString + "extra";

return outString;
}

this will work beautifully

Sally

[Dave Lorde]

Indeed it will. It was your original post that had a void function returning a CString that won't work... :-)

Dave

This may be one solution


// myclass.h

class CMyClass
{
public:
CMyClass();
virtual ~CMyClass();
void CMyAlloc();
CString* m_szText;
};


// myclass.cpp

CMyClass::CMyClass()
{
m_szText = NULL;
}

CMyClass::~CMyClass()
{
if(m_szText != NULL) // Don't delete if not allocated
{
delete m_szText;
m_szText = NULL;
}
}

CMyClass::CMyAlloc()
{
if(m_szText != NULL) // Don't allocat if already allocated
{
m_szText = new CString;
m_szText->Format(_T("%s"), _T("My String"))
}
}

[LALeonard]

Use CString. CString is always at least as efficient as char arrays, and often *more* efficient. Anything you can do with char arrays, you can do with a CString.

CString sMyData;
sMyData = "Lots of data";
DoSomething(sMyData);

// If DoSomething does not modify "sMyData"...
void MyClass::DoSomething(const CString& sMyData)
{
}

// If DoSomething does modify "sMyData"...
void MyClass::DoSomething(CString& sMyData)
{
}

Also, buy a *good* C++ book like "Thinking in C++" or "Effective C++"...

HTH.

LA Leonard - Definitive Solutions, Inc.

[Ran]

How do I use CString in non-mfc appl?
For example: I'm writing a console appl. I have used #include <windows.h>, then there is another header I have to include ~<afx..h>. When I include it it stats it won't work with <windows.h> included. I didn't understand the idea, so I decided not to use CString, which I generally like and use.

Futhermore, If I would like to pass an actual test and not a pointer, how do I do that?

string myfunc ();

string myfunc ()
{
char szBuff[1000];
return (szBuff);
}
How do I get the text, if I don't know the that szBuff is actually [1000]?

[Ran]

How do I use CString in non-mfc appl?
For example: I'm writing a console appl. I have used #include <windows.h>, then there is another header I have to include ~<afx..h>. When I include it it stats it won't work with <windows.h> included. I didn't understand the idea, so I decided not to use CString, which I generally like and use.

Futhermore, If I would like to pass an actual test and not a pointer, how do I do that?

string myfunc ();

string myfunc ()
{
char szBuff[1000];
return (szBuff);
}
How do I get the text, if I don't know the that szBuff is actually [1000]?

btw: without using destructors/constructor clases.