CSVファイルの作成について

sw.Write("""" & a & """" & ",")
sw.Write("""" & b & """" & ",")

strSw = strSw & """" & a & """" & "," & """" & b & """" & "," & c

using System;
using System.IO;
using System.Text;
using System.Collections;
using System.Collections.Specialized;


namespace CSVClass
{
    public interface ICsv : IList
    {
        char Quoted
        {
            get;
            set;
        }
        
        char Delimiter
        {
            get;
            set;
        }

        string CommaStr
        {
            get;
            set;
        }
    }

    public class CommaString : StringCollection, ICsv
    {
        protected char _q = '"';
        protected char _d = ',';

        public string CommaStr
        {
            get {return getCommaStr();}
            set {setCommaStr(value);}
        }

        public char Quoted
        {
            get {return _q;}
            set {_q = value;}
        }
        public char Delimiter
        {
            get {return _d;}
            set {_d = value;}
        }
        
        new public string this[int index]
        {
            get {return base[index];}
            set {base[index] = value;}
        }

        private string getCommaStr()
        {
            StringBuilder sb = new StringBuilder();
            foreach(string s in this)
            {
                sb.Append(_q);
                sb.Append(s);
                sb.Append(_q);
                sb.Append(_d);
            }
            return sb.Remove(sb.Length-1,1).ToString();
        }

        private void setCommaStr(string ACommaStr)
        {
            this.Clear();
            if (ACommaStr.Length == 0)return;
            StringBuilder sb = new StringBuilder(ACommaStr);
            int i = 0;
            string s = "";
            while (true) 
            {
                if (i == sb.Length)
                {
                    s = sb.ToString();
                    base.Add(s);
                    break;
                }
                if (sb[i] == _d)
                {
                    if (i == 0) s = "";
                    else
                    {
                        if (sb[0] == _q)
                        {
                            if (sb[i-1] == _q)
                            {
                                s = sb.ToString().Substring(1,i-2);
                            }
                            else
                            {
                                i++;
                                continue;
                            }
                        } 
                        else s = sb.ToString().Substring(0,i);
                    }
                    sb.Remove(0,i+1);
                    base.Add(s);
                    i = 0;
                } 
                else i++;
            }
        }
    }

    class CommaStrEnumerator: IEnumerator
    {
        int _pos;
        StringCollection list = null;
        public CommaStrEnumerator(StringCollection AList)
        {
            list = AList;
            this.Reset();
        }

        public void Reset()
        {
            _pos = -1;
        }

        public object Current
        {
            get
            {
                ICsv cs = new CommaString();
                cs.CommaStr = list[_pos];
                return cs;
            }
        }

        public bool MoveNext()
        {
            if (_pos >= list.Count-1) return false;
            _pos++;
            return true;
        }
    }

    public class CSV : CommaString, IEnumerable
    {
        new public IEnumerator GetEnumerator()
        {
            return new CommaStrEnumerator(this);
        }

        new public ICsv this[int Row]
        {
            get 
            {
                CommaString cs = new CommaString();
                cs.Delimiter = _d;
                cs.Quoted = _q;
                cs.CommaStr = base[Row];
                return cs;
            }
            set
            {
                base[Row] = value.CommaStr;
            }
        }

        public string this[int Row,int Col]
        {
            get
            {
                return getCommaField(base[Row],Col);
            }
            set
            {
                base[Row] = setCommaField(base[Row],value,Col);
            }

        }

        public CSV():base()
        {
        }
        
        public void LoadFile(string AFileName)
        {
            this.LoadFile(AFileName,Encoding.Default);
        }

        public void LoadFile(string AFileName,Encoding AEncoding)
        {
            using (FileStream fs = new FileStream(AFileName,FileMode.Open))
            {
                using (StreamReader sr = new StreamReader(fs,AEncoding)) 
                {
                    string str;
                    while ((str = sr.ReadLine()) != null) 
                    {
                        base.Add(str);
                    }
                }
            }
        }

        public void SaveFile(string AFileName)
        {
            this.SaveFile(AFileName,Encoding.Default);
        }

        public void SaveFile(string AFileName,Encoding AEncoding)
        {
            using (FileStream fs = new FileStream(AFileName,FileMode.Create))
            {
                using (StreamWriter sw = new StreamWriter(fs,AEncoding)) 
                {
                    foreach(string str in this)
                    {
                        sw.WriteLine(str);    
                    }
                }
            }
        }

        public int AddField(int Row,string value)
        {
            ICsv c = new CommaString();
            c.CommaStr = base[Row];
            int ret = c.Add(value);
            base[Row] = c.CommaStr;
            return ret;
        }

        private string getCommaField(string ACommaStr,int Col)
        {
            ICsv c = new CommaString();
            c.Delimiter = _d;
            c.Quoted = _q;
            c.CommaStr = ACommaStr;
            return (string)c[Col];
        }
        private string setCommaField(string ACommaStr,string AValue,int Col)
        {
            ICsv c = new CommaString();
            c.Delimiter = _d;
            c.Quoted = _q;
            c.CommaStr = ACommaStr;
            if (c.Count > Col)
            {
                c[Col] = AValue;
                return c.CommaStr;
            }
            else
            {
                throw new Exception("配列範囲外");
            }
        }

    }

}