How do you convert a numerical number to an Excel column name in C# without using automation getting the value directly from Excel.
Excel 2007 has a possible range of 1 to 16384, which is the number of columns that it supports. The resulting values should be in the form of excel column names, e.g. A, AA, AAA etc.
Here's how I do it:
private string GetExcelColumnName(int columnNumber)
{
string columnName = "";
while (columnNumber > 0)
{
int modulo = (columnNumber - 1) % 26;
columnName = Convert.ToChar('A' + modulo) + columnName;
columnNumber = (columnNumber - modulo) / 26;
}
return columnName;
}
If anyone needs to do this in Excel without VBA, here is a way:
=SUBSTITUTE(ADDRESS(1;colNum;4);"1";"")
where colNum is the column number
And in VBA:
Function GetColumnName(colNum As Integer) As String
Dim d As Integer
Dim m As Integer
Dim name As String
d = colNum
name = ""
Do While (d > 0)
m = (d - 1) Mod 26
name = Chr(65 + m) + name
d = Int((d - m) / 26)
Loop
GetColumnName = name
End Function
Sorry, this is Python instead of C#, but at least the results are correct:
def ColIdxToXlName(idx):
if idx < 1:
raise ValueError("Index is too small")
result = ""
while True:
if idx > 26:
idx, r = divmod(idx - 1, 26)
result = chr(r + ord('A')) + result
else:
return chr(idx + ord('A') - 1) + result
for i in xrange(1, 1024):
print "%4d : %s" % (i, ColIdxToXlName(i))
Easy with recursion.
public static string GetStandardExcelColumnName(int columnNumberOneBased)
{
int baseValue = Convert.ToInt32('A');
int columnNumberZeroBased = columnNumberOneBased - 1;
string ret = "";
if (columnNumberOneBased > 26)
{
ret = GetStandardExcelColumnName(columnNumberZeroBased / 26) ;
}
return ret + Convert.ToChar(baseValue + (columnNumberZeroBased % 26) );
}
int nCol = 127;
string sChars = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
string sCol = "";
while (nCol >= 26)
{
int nChar = nCol % 26;
nCol = (nCol - nChar) / 26;
// You could do some trick with using nChar as offset from 'A', but I am lazy to do it right now.
sCol = sChars[nChar] + sCol;
}
sCol = sChars[nCol] + sCol;
Update: Peter's comment is right. That's what I get for writing code in the browser. :-) My solution was not compiling, it was missing the left-most letter and it was building the string in reverse order - all now fixed.
Bugs aside, the algorithm is basically converting a number from base 10 to base 26.
Update 2: Joel Coehoorn is right - the code above will return AB for 27. If it was real base 26 number, AA would be equal to A and the next number after Z would be BA.
int nCol = 127;
string sChars = "0ABCDEFGHIJKLMNOPQRSTUVWXYZ";
string sCol = "";
while (nCol > 26)
{
int nChar = nCol % 26;
if (nChar == 0)
nChar = 26;
nCol = (nCol - nChar) / 26;
sCol = sChars[nChar] + sCol;
}
if (nCol != 0)
sCol = sChars[nCol] + sCol;
..And converted to php:
function GetExcelColumnName($columnNumber) {
$columnName = '';
while ($columnNumber > 0) {
$modulo = ($columnNumber - 1) % 26;
$columnName = chr(65 + $modulo) . $columnName;
$columnNumber = (int)(($columnNumber - $modulo) / 26);
}
return $columnName;
}
Same implementation in Java
public String getExcelColumnName (int columnNumber)
{
int dividend = columnNumber;
int i;
String columnName = "";
int modulo;
while (dividend > 0)
{
modulo = (dividend - 1) % 26;
i = 65 + modulo;
columnName = new Character((char)i).toString() + columnName;
dividend = (int)((dividend - modulo) / 26);
}
return columnName;
}
Although there are already a bunch of valid answers1, none get into the theory behind it.
Excel column names are bijective base-26 representations of their number. This is quite different than an ordinary base 26 (there is no leading zero), and I really recommend reading the Wikipedia entry to grasp the differences. For example, the decimal value 702 (decomposed in 26*26 + 26) is represented in "ordinary" base 26 by 110 (i.e. 1x26^2 + 1x26^1 + 0x26^0) and in bijective base-26 by ZZ (i.e. 26x26^1 + 26x26^0).
Differences aside, bijective numeration is a positional notation, and as such we can perform conversions using an iterative (or recursive) algorithm which on each iteration finds the digit of the next position (similarly to an ordinary base conversion algorithm).
The general formula to get the digit at the last position (the one indexed 0) of the bijective base-k representation of a decimal number m is (f being the ceiling function minus 1):
m - (f(m / k) * k)
The digit at the next position (i.e. the one indexed 1) is found by applying the same formula to the result of f(m / k). We know that for the last digit (i.e. the one with the highest index) f(m / k) is 0.
This forms the basis for an iteration that finds each successive digit in bijective base-k of a decimal number. In pseudo-code it would look like this (digit() maps a decimal integer to its representation in the bijective base -- e.g. digit(1) would return A in bijective base-26):
fun conv(m) {
q = f(m / k)
a = m - (q * k)
if (q == 0)
return digit(a)
else
return conv(q) + digit(a);
So we can translate this to C#2 to get a generic3 "conversion to bijective base-k" ToBijective() routine:
class BijectiveNumeration {
private int baseK;
private Func<int, char> getDigit;
public BijectiveNumeration(int baseK, Func<int, char> getDigit) {
this.baseK = baseK;
this.getDigit = getDigit;
}
public string ToBijective(double decimalValue) {
double q = f(decimalValue / baseK);
double a = decimalValue - (q * baseK);
return ((q > 0) ? ToBijective(q) : "") + getDigit((int)a);
}
private static double f(double i) {
return (Math.Ceiling(i) - 1);
}
}
Now for conversion to bijective base-26 (our "Excel column name" use case):
static void Main(string[] args)
{
BijectiveNumeration bijBase26 = new BijectiveNumeration(
26,
(value) => Convert.ToChar('A' + (value - 1))
);
Console.WriteLine(bijBase26.ToBijective(1)); // prints "A"
Console.WriteLine(bijBase26.ToBijective(26)); // prints "Z"
Console.WriteLine(bijBase26.ToBijective(27)); // prints "AA"
Console.WriteLine(bijBase26.ToBijective(702)); // prints "ZZ"
Console.WriteLine(bijBase26.ToBijective(16384)); // prints "XFD"
}
Excel's maximum column index is 16384 / XFD, but this code will convert any positive number.
As an added bonus, we can now easily convert to any bijective base. For example for bijective base-10:
static void Main(string[] args)
{
BijectiveNumeration bijBase10 = new BijectiveNumeration(
10,
(value) => value < 10 ? Convert.ToChar('0'+value) : 'A'
);
Console.WriteLine(bijBase10.ToBijective(1)); // prints "1"
Console.WriteLine(bijBase10.ToBijective(10)); // prints "A"
Console.WriteLine(bijBase10.ToBijective(123)); // prints "123"
Console.WriteLine(bijBase10.ToBijective(20)); // prints "1A"
Console.WriteLine(bijBase10.ToBijective(100)); // prints "9A"
Console.WriteLine(bijBase10.ToBijective(101)); // prints "A1"
Console.WriteLine(bijBase10.ToBijective(2010)); // prints "19AA"
}
1 This generic answer can eventually be reduced to the other, correct, specific answers, but I find it hard to fully grasp the logic of the solutions without the formal theory behind bijective numeration in general. It also proves its correctness nicely. Additionally, several similar questions link back to this one, some being language-agnostic or more generic. That's why I thought the addition of this answer was warranted, and that this question was a good place to put it.
2 C# disclaimer: I implemented an example in C# because this is what is asked here, but I have never learned nor used the language. I have verified it does compile and run, but please adapt it to fit the language best practices / general conventions, if necessary.
3 This example only aims to be correct and understandable ; it could and should be optimized would performance matter (e.g. with tail-recursion -- but that seems to require trampolining in C#), and made safer (e.g. by validating parameters).
private String getColumn(int c) {
String s = "";
do {
s = (char)('A' + (c % 26)) + s;
c /= 26;
} while (c-- > 0);
return s;
}
Its not exactly base 26, there is no 0 in the system. If there was, 'Z' would be followed by 'BA' not by 'AA'.
More than 30 solutions already, but here's my one-line C# solution...
public string IntToExcelColumn(int i)
{
return ((i<16926? "" : ((char)((((i/26)-1)%26)+65)).ToString()) + (i<2730? "" : ((char)((((i/26)-1)%26)+65)).ToString()) + (i<26? "" : ((char)((((i/26)-1)%26)+65)).ToString()) + ((char)((i%26)+65)));
}
Refining the original solution (in C#):
public static class ExcelHelper
{
private static Dictionary<UInt16, String> l_DictionaryOfColumns;
public static ExcelHelper() {
l_DictionaryOfColumns = new Dictionary<ushort, string>(256);
}
public static String GetExcelColumnName(UInt16 l_Column)
{
UInt16 l_ColumnCopy = l_Column;
String l_Chars = "0ABCDEFGHIJKLMNOPQRSTUVWXYZ";
String l_rVal = "";
UInt16 l_Char;
if (l_DictionaryOfColumns.ContainsKey(l_Column) == true)
{
l_rVal = l_DictionaryOfColumns[l_Column];
}
else
{
while (l_ColumnCopy > 26)
{
l_Char = l_ColumnCopy % 26;
if (l_Char == 0)
l_Char = 26;
l_ColumnCopy = (l_ColumnCopy - l_Char) / 26;
l_rVal = l_Chars[l_Char] + l_rVal;
}
if (l_ColumnCopy != 0)
l_rVal = l_Chars[l_ColumnCopy] + l_rVal;
l_DictionaryOfColumns.ContainsKey(l_Column) = l_rVal;
}
return l_rVal;
}
}
Sorry, this is Python instead of C#, but at least the results are correct:
def excel_column_number_to_name(column_number):
output = ""
index = column_number-1
while index >= 0:
character = chr((index%26)+ord('A'))
output = output + character
index = index/26 - 1
return output[::-1]
for i in xrange(1, 1024):
print "%4d : %s" % (i, excel_column_number_to_name(i))
Passed these test cases:
For what it is worth, here is Graham's code in Powershell:
function ConvertTo-ExcelColumnID {
param (
[parameter(Position = 0,
HelpMessage = "A 1-based index to convert to an excel column ID. e.g. 2 => 'B', 29 => 'AC'",
Mandatory = $true)]
[int]$index
);
[string]$result = '';
if ($index -le 0 ) {
return $result;
}
while ($index -gt 0) {
[int]$modulo = ($index - 1) % 26;
$character = [char]($modulo + [int][char]'A');
$result = $character + $result;
[int]$index = ($index - $modulo) / 26;
}
return $result;
}
This is a javascript version according to Graham's code
function (columnNumber) {
var dividend = columnNumber;
var columnName = "";
var modulo;
while (dividend > 0) {
modulo = (dividend - 1) % 26;
columnName = String.fromCharCode(65 + modulo) + columnName;
dividend = parseInt((dividend - modulo) / 26);
}
return columnName;
};
Most of previous answers are correct. Here is one more way of converting column number to excel columns. solution is rather simple if we think about this as a base conversion. Simply, convert the column number to base 26 since there is 26 letters only. Here is how you can do this:
steps:
set the column as a quotient
subtract one from quotient variable (from previous step) because we need to end up on ascii table with 97 being a.
divide by 26 and get the remainder.
here is the code that does this :)
def convert_num_to_column(column_num):
result = ""
quotient = column_num
remainder = 0
while (quotient >0):
quotient = quotient -1
remainder = quotient%26
result = chr(int(remainder)+97)+result
quotient = int(quotient/26)
return result
print("--",convert_num_to_column(1).upper())
This snippet works for A to ZZ column Names
string columnName = columnNumber > 26 ? Convert.ToChar(64 + (columnNumber / 26)).ToString() + Convert.ToChar(64 + (columnNumber % 26)) : Convert.ToChar(64 + columnNumber).ToString();
I'm using this one in VB.NET 2003 and it works well...
Private Function GetExcelColumnName(ByVal aiColNumber As Integer) As String
Dim BaseValue As Integer = Convert.ToInt32(("A").Chars(0)) - 1
Dim lsReturn As String = String.Empty
If (aiColNumber > 26) Then
lsReturn = GetExcelColumnName(Convert.ToInt32((Format(aiColNumber / 26, "0.0").Split("."))(0)))
End If
GetExcelColumnName = lsReturn + Convert.ToChar(BaseValue + (aiColNumber Mod 26))
End Function
If you are wanting to reference the cell progmatically then you will get much more readable code if you use the Cells method of a sheet. It takes a row and column index instead of a traditonal cell reference. It is very similar to the Offset method.
Using this in VB.Net 2005 :
Private Function ColumnName(ByVal ColumnIndex As Integer) As String
Dim Name As String = ""
Name = (New Microsoft.Office.Interop.Owc11.Spreadsheet).Columns.Item(ColumnIndex).Address(False, False, Microsoft.Office.Interop.Owc11.XlReferenceStyle.xlA1)
Name = Split(Name, ":")(0)
Return Name
End Function
Another solution:
private void Foo()
{
l_ExcelApp = new Excel.ApplicationClass();
l_ExcelApp.ReferenceStyle = Excel.XlReferenceStyle.xlR1C1;
// ... now reference by R[row]C[column], Ex. A1 <==> R1C1, C6 <==> R3C6, ...
}
see more here - Cell referencing in Excel for everyone! by Dr Nitin Paranjape
public static string ConvertToAlphaColumnReferenceFromInteger(int columnReference)
{
int baseValue = ((int)('A')) - 1 ;
string lsReturn = String.Empty;
if (columnReference > 26)
{
lsReturn = ConvertToAlphaColumnReferenceFromInteger(Convert.ToInt32(Convert.ToDouble(columnReference / 26).ToString().Split('.')[0]));
}
return lsReturn + Convert.ToChar(baseValue + (columnReference % 26));
}
Typescript
function lengthToExcelColumn(len: number): string {
let dividend: number = len;
let columnName: string = '';
let modulo: number = 0;
while (dividend > 0) {
modulo = (dividend - 1) % 26;
columnName = String.fromCharCode(65 + modulo).toString() + columnName;
dividend = Math.floor((dividend - modulo) / 26);
}
return columnName;
}
Seems like so many answers are much more complex than necessary. Here is a generic Ruby answer based on the recursion described above:
One nice thing about this answer is that it's not limited to the 26 characters of English Alphabet. You can define any range you like in COLUMNS constant and it will do the right thing.
# vim: ft=ruby
class Numeric
COLUMNS = ('A'..'Z').to_a
def to_excel_column(n = self)
n < 1 ? '' : begin
base = COLUMNS.size
to_excel_column((n - 1) / base) + COLUMNS[(n - 1) % base]
end
end
end
# verify:
(1..52).each { |i| printf "%4d => %4s\n", i, i.to_excel_column }
This prints the following, eg:
1 => A
2 => B
3 => C
....
33 => AG
34 => AH
35 => AI
36 => AJ
37 => AK
38 => AL
39 => AM
40 => AN
41 => AO
42 => AP
43 => AQ
44 => AR
45 => AS
46 => AT
47 => AU
48 => AV
49 => AW
50 => AX
51 => AY
52 => AZ
This is a common question asked in coding test. it has some constraints: max columns per row= 702 output should have row number+column name e.g. for 703 answer is 2A. (note: i have just modified existing code from another answer) here is the code for the same:
static string GetExcelColumnName(long columnNumber)
{
//max number of column per row
const long maxColPerRow = 702;
//find row number
long rowNum = (columnNumber / maxColPerRow);
//find tierable columns in the row.
long dividend = columnNumber - (maxColPerRow * rowNum);
string columnName = String.Empty;
long modulo;
while (dividend > 0)
{
modulo = (dividend - 1) % 26;
columnName = Convert.ToChar(65 + modulo).ToString() + columnName;
dividend = (int)((dividend - modulo) / 26);
}
return rowNum+1+ columnName;
}
}
T-SQL (SQL SERVER 18)
Copy of the solution on first page
CREATE FUNCTION dbo.getExcelColumnNameByOrdinal(@RowNum int)
RETURNS varchar(5)
AS
BEGIN
DECLARE @dividend int = @RowNum;
DECLARE @columnName varchar(max) = '';
DECLARE @modulo int;
WHILE (@dividend > 0)
BEGIN
SELECT @modulo = ((@dividend - 1) % 26);
SELECT @columnName = CHAR((65 + @modulo)) + @columnName;
SELECT @dividend = CAST(((@dividend - @modulo) / 26) as int);
END
RETURN
@columnName;
END;
Here is a simpler solution for zero based column Index
public static string GetColumnIndexNumberToExcelColumn(int columnIndex)
{
int offset = columnIndex % 26;
int multiple = columnIndex / 26;
int initialSeed = 65;//Represents column "A"
if (multiple == 0)
{
return Convert.ToChar(initialSeed + offset).ToString();
}
return $"{Convert.ToChar(initialSeed + multiple - 1)}{Convert.ToChar(initialSeed + offset)}";
}
My solution based on Graham, Herman Kan and desseim answers, with using StringBuilder:
internal class Program
{
#region get_excel_col_name
/// <summary>
/// Returns the name of the column by its number
/// </summary>
/// <param name="col_num">Column number</param>
/// <returns>Column name</returns>
/// <remarks>Numbering columns from zero</remarks>
private static string get_excel_col_name(int col_num)
{
StringBuilder sb = new StringBuilder(2);
if (col_num >= 0)
{
do
{
sb.Insert(0, (char)(col_num % 26 + 65));
col_num /= 26;
}
while (--col_num >= 0);
}
return sb.ToString();
}
#endregion
private static void Main(string[] args)
{
Console.WriteLine(get_excel_col_name(34));//outputs AI
Console.ReadKey(true);
}
}
static string[] ExcelColumnAlphabetIdentifiers = new string[] { "", "A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M", "N",
"O", "P", "Q", "R", "S", "T", "U", "V", "W", "X", "Y", "Z" };
public static string ExcelColumnAlphabetIdentifier( int ColumnNumber)
{
StringBuilder sb = new StringBuilder();
int remainder = ColumnNumber;
do
{
sb.Append(ExcelColumnAlphabetIdentifiers[remainder % 26]);
remainder = remainder / 26;
}
while (remainder > 0);
return sb.ToString();
}
Here is my solution in python
import math
num = 3500
row_number = str(math.ceil(num / 702))
letters = ''
num = num - 702 * math.floor(num / 702)
while num:
mod = (num - 1) % 26
letters += chr(mod + 65)
num = (num - 1) // 26
result = row_number + ("".join(reversed(letters)))
print(result)