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CString instead of LPCSTR

Posted by Jon Zyzyck on April 16th, 2002

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A simple routine to allow CString formatted strings to be used wherever a regular LPCSTR would be used, without needing to define a CString (ie, dynamically created and formatted LPCSTR strings)

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Environment: VC6 SP4

Well, I've seen other people asking for a class like this, and I sure wanted one, so I finally wrote one.

Suppose you want to call a routine with a dynamically constructed LPCSTR. You would call it like this:

SampleRoutine( (LPCSTR) csFMT(
                  "Sample dynamic string count(%d) name(%s)",
                  nAnInteger,
                  szAZeroTerminatedString));

The Microsoft CString class provides a Format member routine which provides sprintf-type formatting, without the need to allocate a buffer. The class CString automatically calculates the size of the buffer required, and allocates it. A CString variable, however, must first be declared. This routine allows the CString Format member routine to be used, without needing to declare a CString.

Here is the sample code without using the "csFmt" routine:

  CString csTemp;
  CsTemp.Format("Sample dynamic string count(%d) name(%s)",
                nAnInteger, szAZeroTerminatedString);
  SampleRoutine((LPCSTR) csTemp);

This method doesn't require any subclassing, and is only a short < 10 line routine.

CString csFMT(LPCSTR lpszFormat, ...)
{
    CString csStr;

    va_list argList;
    va_start(argList, lpszFormat);
    csStr.FormatV(lpszFormat, argList);
    return csStr;
}

Downloads

You can cut & paste code from above.


Comments

  • If only Format whould ??

    Posted by Legacy on 06/04/2002 12:00am

    Originally posted by: Boaz Harrosh

    If CString::Format was defined as
    CString& AFX_CDECL Format(LPCTSTR lpszFormat, ...);
    and not:
    void AFX_CDECL Format(LPCTSTR lpszFormat, ...);

    than we could just do:
    cout << (LPCSTR)CString().Format("%s" ,"yes it works this way") ;


    A constructor is callable in C++. It is just like a type cast.

    Reply

  • Another way

    Posted by Legacy on 04/17/2002 12:00am

    Originally posted by: Mathieu Fr. 

    You can also do such a thing. No cstring. no alloc.

    Of course there are restrictions due to the static buffer, but SPEED matters sometimes (and mem alloc too) !


    LPCSTR poil(LPCSTR lpszFormat, ...)

    {

        const char buff[1000];

        va_list argList;

        va_start(argList, lpszFormat);

        vsprintf( buff, lpszFormat, argList );

        return buff;

    }

    Reply

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