常用演算法(C#): 二進位,八進位,十六進位數轉換為十進位數的演算法

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;

namespace ExToD
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        //參數Num為需要轉換的數，n為該數的進位
        public string ToD(string Num, int n)
        {
            char[] nums=Num.ToCharArray ();
            int d = 0;
            for (int i = 0; i <nums.Length ; i++)
            {
                string number=nums [i].ToString ();
                if (n == 16)
                {
                    switch (number.ToUpper ())
                    {
                        case "A":
                            number = "10";
                            break;
                        case "B":
                            number = "11";
                            break;
                        case "C":
                            number = "12";
                            break;
                        case "D":
                            number = "13";
                            break;
                        case "E":
                            number = "14";
                            break;
                        case "F":
                            number = "15";
                            break;
                    }
 
                }
                Double power = Math.Pow(Convert.ToDouble (n),Convert.ToDouble ( nums.Length - (i + 1)));
                d = d + Convert.ToInt32 (number) * Convert.ToInt32 (power);
            }
            return d.ToString ();
        }

        private void btnBtoD_Click(object sender, EventArgs e)
        {
            this.txtBtoD.Text = ToD(this.txtB.Text, 2);//將二進位轉換為十進位
        }
        private void btnOtoD_Click(object sender, EventArgs e)
        {
            this.txtOtoD.Text = ToD(this.txtO.Text, 8);//將八進位轉換為十進位
        }

        private void btnXtoD_Click(object sender, EventArgs e)
        {
            this.txtXtoD.Text = ToD(this.txtX.Text, 16);//將十六進位轉換為十進位
        }

        //只允許輸入0、1和退格鍵
        private void txtB_KeyPress(object sender, KeyPressEventArgs e)
        {
            if (e.KeyChar != 48&&e.KeyChar!=49&&e.KeyChar!=8)
            {
                e.Handled = true;
            }
        }
        //只允許輸入0～8和退格鍵
        private void txtO_KeyPress(object sender, KeyPressEventArgs e)
        {
            if (!(e.KeyChar >= 48 && e.KeyChar <= 55) && e.KeyChar != 8)
            {
                e.Handled = true;
            }
        }
        //只允許輸入0～9、a~f和退格鍵
        private void txtX_KeyPress(object sender, KeyPressEventArgs e)
        {
           
            if (!(e.KeyChar >= 48 && e.KeyChar <= 57) && !(e.KeyChar >= 97 && e.KeyChar <= 102) && e.KeyChar != 8)
            {
                e.Handled = true;
            }
        }
       

    }
}