How to convert binary to decimal

Question

How can I convert a binary string, such as 1001101 to Decimal? (77)

Answer 1

If you're after a manual way instead of using built in C# libraries, this would work:

static int BinaryToDec(string input)
{
    char[] array = input.ToCharArray();
    // Reverse since 16-8-4-2-1 not 1-2-4-8-16. 
    Array.Reverse(array);
    /*
     * [0] = 1
     * [1] = 2
     * [2] = 4
     * etc
     */
    int sum = 0; 

    for(int i = 0; i < array.Length; i++)
    {
        if (array[i] == '1')
        {
            // Method uses raising 2 to the power of the index. 
            if (i == 0)
            {
                sum += 1;
            }
            else
            {
                sum += (int)Math.Pow(2, i);
            }
        }

    }

    return sum;
}