C++ unicode box character drawing when overloading I/O operators - c++

Question

I just read Joel's blog post on unicode, and found the characters the I want to use to draw boxes in the console in this pdf from the unicode website.
Displaying these characters is simple enough when done directly with cout, i.e. the following does what it is supposed to do..
cout << u8"\u256C";
However, I am doing some overloading as shown in the following snippets, and I cannot figure out how to get the box characters to display correctly.
I render my data like so ...
// This is the main rendering code
ostream& operator<<(ostream& os, const DataGrid& dg)
{
for(auto row : dg.data)
{
string tmp; //Make empty string
for(auto col : row)
tmp.append( 1, dg.gfxString[col] );
os << tmp << endl;
}
return os;
}
Make it friends with my data model...
class DataGrid
{
public:
friend ostream& operator<<(ostream& os, const DataGrid& dg);
//EDIT: rest of class added on request
DataGrid(Rectangle _rect = Rectangle(Point(0,0), Point(5,5))) :
rect(_rect),
data ( vector<vector<p_t>> (_rect.getHeight(), vector<p_t>(_rect.getWidth(), p_t::EMPTY)) ){}
void addPoint(Point p, p_t type)
{
data[p.getY()][p.getX()] = type;
}
void addBorder()
{
//Top and bottom
fill_n(data[0].begin()+1, rect.getWidth()-2, p_t::BORDER_T);
fill_n(data[rect.getBtm()].begin()+1, rect.getWidth()-2, p_t::BORDER_B);
//Left and right hand border edges
for (int nn=1; nn<rect.getHeight()-1; ++nn){
addPoint(Point(rect.getLeft(), nn), p_t::BORDER_L);
addPoint(Point(rect.getRight(), nn), p_t::BORDER_R);
}
//Corners
addPoint(rect.getTL(), p_t::BORDER_TL);
addPoint(rect.getTR(), p_t::BORDER_TR);
addPoint(rect.getBL(), p_t::BORDER_BL);
addPoint(rect.getBR(), p_t::BORDER_BR);
}
private:
Rectangle rect;
vector<vector<p_t>> data; //p_t is an enum
//string gfxString = " abcdefghijklmnop"; //This works fine
string gfxString = u8"\u256C\u256C\u256C\u256C\u256C\u256C\u256C\u256C"; //Nope
};
Then attempt to render it with the following, but get gibberish ...
DataGrid p = DataGrid(Rectangle(Point(0,0), 40, 10));
p.addBorder();
cout << p;
If anyone can spot a fix, then that would be great. Thanks for reading.

Answer 1

I'd change gfxString to a vector of std::strings (or even a std::array):
// Probably in the final code, these are not all the same value
std::array<std::string, 8> gfxString = {
{ u8"\u256C"
, u8"\u256C"
, u8"\u256C"
, u8"\u256C"
, u8"\u256C"
, u8"\u256C"
, u8"\u256C"
, u8"\u256C"
}};
Or even just an array of const char*.