std::ostringstream to get CString::GetBufferSetLength()-like functionality?

[ibox73]

Hi there,
Can std::ostringstream be used to get CString::GetBufferSetLength()-like functionality? CString provides rather convenient way to use it as a buffer, in particular for winapi functions.

//just an illustration
CString str;
SHGetSpecialFolderPath( 0, str.GetBufferSetLength(..
return str;
 

Is it possible to do such a trick using std::ostringstream? // wostringstream, to be more accurate
Thanks in advance

[weaknessforcats]

I would use an STL vector as a buffer since it is implemented as a array and you have access to the array. Then vector::capacity would get you the current buffer length.

[ibox73]

Thank you for your reply. The whole CString trick is that you can use say the stack string variable as a buffer and then return it, so no copying is fulfilled. Additional buffer can be declared as char[] equally well, but the problem is the ownership for it cannot be delegated to the return result AFAIK.

[weaknessforcats]

To avoid unnecessary copies use a reference.

vector<int> arr;
 
funct(arr);
 

where

void funct(vector<int>& data)
{
 
}

Inside the function funct, data is the same variable as arr. data is just an alias for arr. No copy is made on the call.

[ibox73]

The function I have to write must return string, not an array, so unfortunately this doesn't suit.

[weaknessforcats]

So have the fuction return a string. In that case you have a vector<char> so you can use that as an argument to the string constructor:

string funct(vector<char>& data)
{
     //some processing
     return string(&data[0], data.size());
}

[ibox73]

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[ibox73]

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[ibox73]

Even I haven't found a std-based replacement for the old sweet CStrings's getbuffersetlength, - thank you very much, weaknessforcats, for your replies!

[weaknessforcats]

getbuffersetlength is weakness of CString because it exposes the underlying implementation. When you use it you tie your application to that implementation forever.

Breaking your app while redesigning CString is a big no-no. Therefore CString is now frozen as far as you are concerned. The safe thing to do now is to embed the CString code in your app so you have control over the implementation you used to build the app.