C = a cell or range (optional)
COL returns the column index of the cell referenced by C, or the left-most column if C is a range, or the column in which the formula appears if C is omitted.
The value returned by COL is zero-based; i.e., column A is 0, column B is 1, etc. The value returned by COLUMN is one-based for compatibility with Excel; i.e., column A is 1, column B is 2, etc.
COL(A1) = 0
COL(F10..G19) = 5
COL() = 25, where COL() is in cell Z20.
COLUMN() = 26, where COLUMN() is in cell Z20.
Excel function: COLUMN