private static string parse_Equation(char[] expr, int index)
{
CalculatorLogic cl = new CalculatorLogic();
string num = "";
if((int)expr[index]==83){
index += 4;
if((int)expr[index]==32){
for(int i = index; i<= expr.Length-2;i++)
num += expr [i].ToString();
}
double srt_num = double.Parse (num);
IUnaryOperator sqrt = new Sqrt ();
return Convert.ToString(sqrt.perform (srt_num));
}
if((int)expr[index]==82){
index += 10;
if((int)expr[index]==32){
for(int i = index; i<= expr.Length-2;i++)
num += expr [i].ToString();
}
double srt_num = double.Parse (num);
IUnaryOperator reci = new Reciprocal ();
return Convert.ToString(reci.perform (srt_num));
}
if((int)expr[index]==78){
index += 6;
if((int)expr[index]==32){
for(int i = index; i<= expr.Length-2;i++)
num += expr [i].ToString();
}
double srt_num = double.Parse (num);
IUnaryOperator neg = new Negate ();
return Convert.ToString(neg.perform (srt_num));
}
while (index != expr.Length - 1) {
double x = getDouble (expr, ref index);
char op = expr [index];
index++;
if (op == '\r') {
cl.AcceptNumber (x, null);
string result = cl.Equals ();
return result;
}
perform_op (x, op, cl);
}
return "";
//return value;
}
private static void perform_op(double x, char op, CalculatorLogic cl)
{
IBinaryOperator subOperator = new SubtractionOperator();
IBinaryOperator mulOperator = new MultiplicationOperator();
IBinaryOperator divOperator = new DivisionOperator();
IBinaryOperator addOperator = new AdditionOperator();
if (op == '+')
cl.AcceptNumber (x, addOperator);
else
if (op == '-')
cl.AcceptNumber (x, subOperator);
else
if (op == '*')
cl.AcceptNumber (x,mulOperator);
else
if (op == '/')
cl.AcceptNumber (x, divOperator);
}