void remove_whitespace(string str = "ab\tc d e f   g")
{
	str.Replace('\t', ' '); // replace all tabs with black
	
	vector<string> vs;
	str.GetTokens(vs, ' '); // get each token seperated by black 
	
	// append sub string from vs to one string
	string strTemp;
	for(int nn = 0; nn < vs.GetSize(); nn++)
		strTemp += (vs[nn]);
	
	str = strTemp;
	out_str(str);
}

str.Remove(' ');
str.Remove('\t');