Extended ascii json & xml

Hello,
I try to use extended ascii with json and xml parsing.
When I get string value I have twice character for special character

Twice character :
“â”
“ä”

Instead of :
“â”
“ä”

See after 127 :
http://www.utf8-chartable.de/unicode-utf8-table.pl?utf8=dec

Special character begin with 194 or 195 !

I’m looking for a simply solution !

Something that :

string toAscciExt(const string& str)
{
	stringstream ss;
	for(int i = 0 ; i < str.length() ; i++)
	{
		if (i < str.length() -1) {
			if (str[i] == char(195)) {
				ss << (char)(str[i + 1] + 64);
				i++;
			}
			else if (str[i] == char(194)) {
				ss << (char)str[i + 1];
				i++;
			}
			else {
				ss << str[i];
			}
		}
		else {
			ss << str[i];
		}
	}
	return ss.str();
}