Excel 열 문자 및 숫자 변환

인터넷에서 본 것

// excel ， 1 

        public  int ToIndex(string columnName)

        {

            if (!Regex.IsMatch(columnName.ToUpper(), @"[A-Z]+"))

                throw new Exception("Invalid parameter");

            int index = 0;

            char[] chars = columnName.ToUpper().ToCharArray();

            for (int i = 0; i < chars.Length; i++)

            {

                index += ((int)chars[i] - (int)'A' + 1) * (int)Math.Pow(26, chars.Length - i - 1);

            }

            return index;

        }

.csharpcode, .csharpcode pre
{
font-size: small;
color: black;
font-family: consolas, "Courier New", courier, monospace;
background-color: #ffffff;
/*white-space: pre;*/
}
.csharpcode pre { margin: 0em; }
.csharpcode .rem { color: #008000; }
.csharpcode .kwrd { color: #0000ff; }
.csharpcode .str { color: #006080; }
.csharpcode .op { color: #0000c0; }
.csharpcode .preproc { color: #cc6633; }
.csharpcode .asp { background-color: #ffff00; }
.csharpcode .html { color: #800000; }
.csharpcode .attr { color: #ff0000; }
.csharpcode .alt
{
background-color: #f4f4f4;
width: 100%;
margin: 0em;
}
.csharpcode .lnum { color: #606060; }

 // excel ， A ， A 1 

        public string ToName(int index)

        {

            if (index <= 0)

                throw new Exception("invaild parameter");

            

            index--;

            List<string> chars = new List<string>();

            do

            {

               if (chars.Count > 0)

                   index--;

                chars.Insert(0, ((char)(index % 26 + (int)'A' )).ToString());

                index = (int)((index - index % 26) / 26);

            } while (index > 0);

            

            return String.Join(string.Empty, chars.ToArray());

        }

.csharpcode, .csharpcode pre
{
font-size: small;
color: black;
font-family: consolas, "Courier New", courier, monospace;
background-color: #ffffff;
/*white-space: pre;*/
}
.csharpcode pre { margin: 0em; }
.csharpcode .rem { color: #008000; }
.csharpcode .kwrd { color: #0000ff; }
.csharpcode .str { color: #006080; }
.csharpcode .op { color: #0000c0; }
.csharpcode .preproc { color: #cc6633; }
.csharpcode .asp { background-color: #ffff00; }
.csharpcode .html { color: #800000; }
.csharpcode .attr { color: #ff0000; }
.csharpcode .alt
{
background-color: #f4f4f4;
width: 100%;
margin: 0em;
}
.csharpcode .lnum { color: #606060; }