COLUMN - find current column on I/O unit.

B:
   col = column( [unit] );
C:
   int column(FILE *unit);

unit: is the unit for which the column is to be determined. This may be an input or output unit. The default is the current write unit.
col: is the column that the next character will be written to or read from.

COLUMN determines the current column position on the specified I/O stream. The following rules apply:

Columns are numbered starting at 1.
On input units, tab characters count as one character. On output units, tabs count as one character if you haven't set any tab stops; otherwise, a tab character moves to the next column where a tab stop has been set.
Control characters do not add to the column count; in other words, they have a width of zero.
If the last character was a new-line or a carriage return, COLUMN returns the length of the preceding line. The column position is then reset to 1 again.

The COLUMN function is not supported with strings that have been opened for I/O.