Code Golf: Numeric equivalent of an Excel column name

Answer 1

Excel (not cheating), 25 chars

Supports up to XFD:

=COLUMN(INDIRECT(A1&"1"))

Installation:

2. Put the formula in cell A2.

Usage:

1. Enter the column string in cell A1.
2. Read the result at cell A2.

---

54 chars, plus a lot of instructions

Supports ROFL also:

(A2)  =MAX(B:B)
(B2)  =IFERROR(26*B1+CODE(MID(A$1,ROW()-1,1))-64,0)

Installation:

1. Clear the whole spreadsheet.
2. Put the formula (A2) in cell A2.
3. Put the formula (B2) in cell B2.
4. Fill formula (B2) to as far down as possible.

Usage:

4. Enter the column string in cell A1.
5. Read the result at cell A2.

Answer 2

JavaScript 1.8: 66 characters

function a(p)Array.reduce(p,function(t,d)t*26+d.charCodeAt()-64,0)

Javascript 1.8: 72 characters

function a(p)(t=0,p.replace(/./g,function(d)t=t*26+d.charCodeAt()-64),t)

JavaScript 1.6: 83 characters

function a(p){t=0;p.split("").map(function(d){t=t*26+d.charCodeAt(0)-64});return t}

JavaScript: 95 characters

function a(p){r=0;t=1;l=p.length;for(i=0;i<l;i++){r+=(p.charCodeAt(l-1-i)-64)*t;t*=26}return r}

JavaScript: 105 characters

function a(p,i){i=i||0;l=p.length;return p?(p.charCodeAt(l-1)-64)*Math.pow(26,i)+a(p.slice(0,l-1),i+1):0}

Usage:

a("A")        // 1
a("B")        // 2
a("AD")       // 30
a("ABC")      // 731
a("WTF")      // 16074
a("ROFL")     // 326676

Answer 3

C# 156 146 118 Chars

using System.Linq;class P{static void Main(string[]a){System.Console.Write(
a[0].Aggregate(0,(t,c)=>(t+c-64)*26)/26);}}

Ungolfed:

using System.Linq;
class P
{
    static void Main(string[] a)
    {
        System.Console.Write(a[0]
            .Aggregate(0, (t, c) => (t + c - 64) * 26) / 26);
    }
}

Answer 4

Python, 64 49 characters

s=0
for c in raw_input():s=26*s+ord(c)-64
print s

You can also replace raw_input() with input() to reduce the character count by 4, but that then requires the input to contain quotation marks around it.

And here's a subroutine that clocks in at 47 characters:

f=lambda x:len(x)and 26*f(x[:-1])+ord(x[-1])-64

Answer 5

Explanation of Concepts - Excelcification

Nice. I wrote my own version of this with a little more explanation a long time ago at http://aboutdev.wordpress.com/2009/12/19/excelcification-brain-teaser-code/. Although it's not quite an optimized version!

FYI. The base 26 arithmetic is called hexavigesimal and Excel's maximum column is XFD which converts to 16383 (using 0 as the first cell) which is coincidentally exactly 2^14 cells.

Can anyone guess as to why it is 2^14??

Answer 6

Excel, 9 chars :)

Use the right tool for the job:

=COLUMN()