Code Golf: Numeric equivalent of an Excel column name

[ForumBot]

The challenge

The shortest code by character count that will output the numeric equivalent of an Excel column string.

For example, the A column is 1, B is 2, so on and so forth. Once you hit Z, the next column becomes AA, then AB and so on.

Test cases:

A:    1
B:    2
AD:   30
ABC:  731
WTF:  16074
ROFL: 326676

Code count includes input/output (i.e full program).

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Source : Stack Overflow

[ayi]

Perl, 36 34 33 31 30 17 15 11 characters

$_=()=A..$_

Usage:

$ echo -n WTF | perl -ple '$_=()=A..$_'
16074

Reduced to 17 by using echo -n to avoid a chop call.

Reduced to 15 by using say instead of print.

Reduced to 11 by using -p instead of say.

Explanation:

A is evaluated in string context and A..$_ builds a list starting at “A” and string-incrementing up to the input string. Perl interprets the ++ operator (and thus ..) on strings in an alphabetic context, so for example $_="AZ";$_++;print outputs BA.

=()= (aka “goatse” operator) forces an expression to be evaluated in list context, and returns the number of elements returned by that expression i.e., $scalar = () = <expr> corresponds to @list = <expr>; $scalar = @list.