Fastest function to generate Excel column letters in C#

by

I currently use this, with Excel 2007

public static string ExcelColumnFromNumber(int column)
        {
            string columnString = "";
            decimal columnNumber = column;
            while (columnNumber > 0)
            {
                decimal currentLetterNumber = (columnNumber - 1) % 26;
                char currentLetter = (char)(currentLetterNumber + 65);
                columnString = currentLetter + columnString;
                columnNumber = (columnNumber - (currentLetterNumber + 1)) / 26;
            }
            return columnString;
        }

and 

public static int NumberFromExcelColumn(string column)
        {
            int retVal = 0;
            string col = column.ToUpper();
            for (int iChar = col.Length - 1; iChar >= 0; iChar--)
            {
                char colPiece = col[iChar];
                int colNum = colPiece - 64;
                retVal = retVal + colNum * (int)Math.Pow(26, col.Length - (iChar + 1));
            }
            return retVal;
        }

As mentioned in other posts, the results can be cached.

More Related Contents:

  1. Excel Interop – Efficiency and performance
  2. Is a LINQ statement faster than a ‘foreach’ loop?
  3. How to detect installed version of MS-Office?
  4. Export DataTable to Excel with EPPlus
  5. C# ‘is’ operator performance
  6. Performance difference for control structures ‘for’ and ‘foreach’ in C#
  7. How to read file using NPOI
  8. Server execution failed (Exception from HRESULT: 0x80080005 (CO_E_SERVER_EXEC_FAILURE))
  9. How to create CSV Excel file C#? [closed]
  10. Performance of static methods vs instance methods
  11. How to open an Excel file in C#?
  12. When is optimization premature? [closed]
  13. Advantages to Using Private Static Methods
  14. Static vs. non-static method
  15. Get instance of Excel application with C# by Handle
  16. Is there any performance difference between ++i and i++ in C#?
  17. C# quickest way to shift array
  18. System.Net.WebClient unreasonably slow
  19. EPPlus Large Dataset Issue with Out of Memory Exception
  20. How much faster is C++ than C#?
  21. No definition found for GetActiveObject from System.Runtime.InteropServices.Marshal C#
  22. Console.WriteLine slow
  23. Reading from Excel (Range into multidimensional Array) C#
  24. How do I measure how long a function is running?
  25. How to read last “n” lines of log file [duplicate]
  26. Get all files and directories in specific path fast
  27. Using ExcelDataReader to read Excel data starting from a particular cell
  28. Performance of compiled-to-delegate Expression
  29. EPPlus – LoadFromCollection – Text converted to number
  30. .Net Excel Interop Deleting a worksheet

Leave a Comment