using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace CalculatorApplication
{
class Calculator
{
string input;
char[] szArr;
int length ;
int current = -1;
char ch;
public Calculator(String input)
{
this.input = input;
szArr = input.ToCharArray();
length = szArr.Length;
}
char nextToken()
{
++current;
if(current==length) return 'p';
return szArr[current];
}
public double expression()
{
double d = term();
while(true){
switch (ch)
{
case '+':
d+= term();
break;
case '-':
d -= term();
break;
default:
break;
}
if (ch == 'p') break;
}
return d;
}
public double term()
{
double d = primary();
switch (ch)
{
case '*':
d *= primary();
break;
case '/':
d /= primary();
break;
default:
break;
}
return d;
}
public double primary()
{
string str = "";
double value = 0.0;
while (true)
{
ch = nextToken();
if (isDigit(ch))
{
str += ch;
}
else
{
break;
}
}
value = double.Parse(str);
return value;
}
bool isDigit(char ch)
{
return ch == '0' || ch == '1' || ch == '2' || ch == '3' || ch == '4' || ch == '5' || ch == '6' || ch == '7' || ch == '8' || ch == '9';
}
}
class Program
{
static void Main(string[] args)
{
Console.WriteLine("Enter expression");
string input = Console.ReadLine();
Console.WriteLine(new Calculator(input).expression());
}
}
}