C#.Net获取磁盘的空间大小

下面直接上代码

 private void button1_Click(object sender, EventArgs e)
        {
            string strRecordFilePath = "d:/dasda";
            string str=strRecordFilePath.Substring(0, 1).ToUpper();//取首字母并转为大写
            this.m_ChkDisk(str);
        }

    //strDisk应为大写,如 "D"

        private void m_ChkDisk(string strDisk)
        {
            if (strDisk == "")
                return;

            txtTotal.Text = GetHardDiskSpace(strDisk).ToString();
            txtFreeSpace.Text = GetHardDiskFreeSpace(strDisk).ToString();
            int a, b, c;
            a = Convert.ToInt32(txtTotal.Text);
            b = Convert.ToInt32(txtFreeSpace.Text);
            c = a - b;
            
            txtUse.Text=c.ToString();
        }

        ///  <summary> 
        /// 获取指定驱动器的空间总大小(单位为B) 
        ///  </summary> 
        ///  <param name="str_HardDiskName">只需输入代表驱动器的字母即可 (大写)</param> 
        ///  <returns> </returns> 
        public static long GetHardDiskSpace(string str_HardDiskName) 
        { 
            long totalSize= new long(); 
            str_HardDiskName=str_HardDiskName +":\\"; 
            System.IO.DriveInfo[] drives = System.IO.DriveInfo.GetDrives(); 
            foreach (System.IO.DriveInfo drive in drives) 
            { 
                if (drive.Name == str_HardDiskName) 
                {
                    totalSize = drive.TotalSize / (1024 * 1024 * 1024); 
                } 
            } 
            return totalSize; 
        }

        ///  <summary> 
        /// 获取指定驱动器的剩余空间总大小(单位为B) 
        ///  </summary> 
        ///  <param name="str_HardDiskName">只需输入代表驱动器的字母即可 </param> 
        ///  <returns> </returns> 
        public static long GetHardDiskFreeSpace(string str_HardDiskName) 
        { 
            long freeSpace = new long(); 
            str_HardDiskName = str_HardDiskName + ":\\"; 
            System.IO.DriveInfo[] drives = System.IO.DriveInfo.GetDrives(); 
            foreach (System.IO.DriveInfo drive in drives) 
            { 
                if (drive.Name == str_HardDiskName) 
                {
                    freeSpace = drive.TotalFreeSpace / (1024 * 1024 * 1024); 
                } 
            } 
            return freeSpace; 
        }