Version: 3.0.4
wxStringBufferLength Class Reference

#include <wx/string.h>

Detailed Description

This tiny class allows you to conveniently access the wxString internal buffer as a writable pointer without any risk of forgetting to restore the string to the usable state later, and allows the user to set the internal length of the string.

For example, assuming you have a low-level OS function called "int GetMeaningOfLifeAsString(char *)" copying the value in the provided buffer (which must be writable, of course), and returning the actual length of the string, you might call it like this:

wxString theAnswer;
wxStringBufferLength theAnswerBuffer(theAnswer, 1024);
int nLength = GetMeaningOfLifeAsString(theAnswerBuffer);
theAnswerBuffer.SetLength(nLength);
if ( theAnswer != "42" )
wxLogError("Something is very wrong!");

Note that the exact usage of this depends on whether or not wxUSE_STL is enabled. If wxUSE_STL is enabled, wxStringBuffer creates a separate empty character buffer, and if wxUSE_STL is disabled, it uses GetWriteBuf() from wxString, keeping the same buffer wxString uses intact. In other words, relying on wxStringBuffer containing the old wxString data is not a good idea if you want to build your program both with and without wxUSE_STL.

Note that wxStringBuffer::SetLength must be called before wxStringBufferLength destructs.

Library:  wxBase
Category:  Data Structures

Public Member Functions

 wxStringBufferLength (const wxString &str, size_t len)
 Constructs a writable string buffer object associated with the given string and containing enough space for at least len characters. More...
 
 ~wxStringBufferLength ()
 Restores the string passed to the constructor to the usable state by calling wxString::UngetWriteBuf on it. More...
 
void SetLength (size_t nLength)
 Sets the internal length of the string referred to by wxStringBufferLength to nLength characters. More...
 
wxCharoperator wxChar * ()
 Returns the writable pointer to a buffer of the size at least equal to the length specified in the constructor. More...
 

Constructor & Destructor Documentation

wxStringBufferLength::wxStringBufferLength ( const wxString str,
size_t  len 
)

Constructs a writable string buffer object associated with the given string and containing enough space for at least len characters.

Basically, this is equivalent to calling wxString::GetWriteBuf and saving the result.

wxStringBufferLength::~wxStringBufferLength ( )

Restores the string passed to the constructor to the usable state by calling wxString::UngetWriteBuf on it.

Member Function Documentation

wxChar* wxStringBufferLength::operator wxChar * ( )

Returns the writable pointer to a buffer of the size at least equal to the length specified in the constructor.

void wxStringBufferLength::SetLength ( size_t  nLength)

Sets the internal length of the string referred to by wxStringBufferLength to nLength characters.

Must be called before wxStringBufferLength destructs.