change string to integer without using typecasting in C#

Parse the string into chars, multiply each char int value by 10^(reversed index of char);

using System;
using System.Linq;

namespace ParseTest
{
    public class Program
    {
        static void Main()
        {
            var s = "129";
            var r = s.Reverse();
            var sum = 0;
            for (var i = 0; i < r.Count(); ++i)
            {
                sum += (r.ElementAt(i) - '0') * (int)Math.Pow(10, i);
            }

            Console.WriteLine("int is {0}", sum);
        }

    }
}

Also, I don't think I need to point out that you shouldn't be doing this if this is for a real application, use the built in conversions instead.

But, for as a purely academic exercise, the above should work.

Hope this helps,
Fredrik

I am not sure if Google [^]is broken at your place? Or they blocked MSDN?

Look at the MSDN documentation to do this.

http://msdn.microsoft.com/en-us/library/vstudio/bb397679.aspx[^]

I would recommend to look into

Int32.TryParse(string, out int)

as well.

It's not possible!

Please, read it: Casting and Type Conversions (C# Programming Guide)[^]

MSDN:

Because C# is statically-typed at compile time, after a variable is declared, it cannot be declared again or used to store values of another type unless that type is convertible to the variable's type. For example, there is no conversion from an integer to any arbitrary string. Therefore, after you declare i as an integer, you cannot assign the string "Hello" to it, as is shown in the following code.