How to convert numbers between hexadecimal and decimal

Question

How do you convert between hexadecimal numbers and decimal numbers in C#?

Answer 1

My solution is a bit like back to basics, but it works without using any built-in functions to convert between number systems.

    public static string DecToHex(long a)
    {
        int n = 1;
        long b = a;
        while (b > 15)
        {
            b /= 16;
            n++;
        }
        string[] t = new string[n];
        int i = 0, j = n - 1;
        do
        {
                 if (a % 16 == 10) t[i] = "A";
            else if (a % 16 == 11) t[i] = "B";
            else if (a % 16 == 12) t[i] = "C";
            else if (a % 16 == 13) t[i] = "D";
            else if (a % 16 == 14) t[i] = "E";
            else if (a % 16 == 15) t[i] = "F";
            else t[i] = (a % 16).ToString();
            a /= 16;
            i++;
        }
        while ((a * 16) > 15);
        string[] r = new string[n];
        for (i = 0; i < n; i++)
        {
            r[i] = t[j];
            j--;
        }
        string res = string.Concat(r);
        return res;
    }