Code Golf: Numeric equivalent of an Excel column name

Answer 1

Common Lisp, 103 128 characters

(defun x(s)(reduce(lambda(x y)(+(* 26 x)y))(map 'vector(lambda(b)(-(char-code b)(char-code #\A)-1))s)))

Answer 2

C#, 117 111 chars

No contest compared to the likes of Perl, Ruby and APL but an improvement on the other C#/Java answers given so far.

This uses Horner's rule.

class C{static void Main(string[]a){int t=0;foreach(var c in a[0]){t=(t+c-64)*26;}System.Console.Write(t/26);}}

Answer 3

Python - 63 chars

>>> f=lambda z: reduce(lambda x,y: 26*x+y, [ord(c)-64 for c in z])

>>> f('ROFL')

326676

Answer 4

Haskell, 50 51 56 chars

main=interact$show.foldl(\x->(26*x-64+).fromEnum)0

Usage:

~:166$ echo -n "ROFL" | ./a.out
326676
~:167$ echo -n "WTF" | ./a.out
16074

Answer 5

Powershell, 42 chars

[char[]]$args[($s=0)]|%{$s=$s*26+$_-64};$s

Answer 6

Common Lisp, 86 characters.

(defun z(s)(let((a 0))(map nil(lambda(v)(setf a(+(* 26 a)(digit-char-p v 36)-9)))s)a))