Copy a string to clipboard in Linux KDE Plasma

I am doing a GUI program in C++ and I use OpenSuse with KDE Plasma. I would like to copy to clipboard a string. How can I accomplish that? Here is my code:

#include <wx_pch.h>
#include <wx.msgdlg.h>
#include <string>
#include <fstream>
#include <vector>
#include <sstream>
void SimpleGUIFrame::CopyToClipboard(string str) 
{ 
  // copy str to cliboard
}