Convert Hex to Double

Question

how do you set specific bits for a double?

For an int I\'d do something like this:

public static int Value { get { return 0xfff8; } }

Answer 1

I just looked into the topic of converting a Hex string of a Double Value back into a Double Value. I found some usefull sites. This Site shows how to calculate a double value: https://gregstoll.dyndns.org/~gregstoll/floattohex/ This shows how decimal point fractals are calulated(binary excample) https://www.geeksforgeeks.org/convert-binary-fraction-decimal/

My example input value is 40C688C000000000, resulting in 11537.5 Important are the first 3 Hex Values, because they are the exponent used for the Double Value. The Amount of Hex Values after this doesn't really matter.

This is the simple Code I created from this Information:

public static double DoubleFromHex(string hex)
{
    int exponent;
    double result;
    string doubleexponenthex = hex.Substring(0, 3);
    string doublemantissahex = hex.Substring(3);
    double mantissavalue = 1; //yes this is how it works

    for (int i = 0; i < doublemantissahex.Length; i++)
    {
        int hexsignvalue = Convert.ToInt32(doublemantissahex.Substring(i, 1),16); //Convert ,16 Converts from Hex
        mantissavalue += hexsignvalue * (1 / Math.Pow(16, i+1));
    }

    exponent = Convert.ToInt32(doubleexponenthex, 16);
    exponent = exponent - 1023;  //just how it works

    result = Math.Pow(2, exponent) * mantissavalue;
    return result;
}