The column functions convert between a character position (counting characters from the beginning of the buffer) and a column position (counting screen characters from the beginning of a line).
These functions count each character according to the number of
columns it occupies on the screen. This means control characters count
as occupying 2 or 4 columns, depending upon the value of
ctl-arrow, and tabs count as occupying a number of columns that
depends on the value of
tab-width and on the column where the tab
begins. See Usual Display Conventions.
Column number computations ignore the width of the window and the
amount of horizontal scrolling. Consequently, a column value can be
arbitrarily high. The first (or leftmost) column is numbered 0. They
also ignore overlays and text properties, aside from invisibility.
Invisible text is considered as having zero width, unless
buffer-invisibility-spec specifies that invisible text should
be displayed as ellipsis (see Invisible Text).
This function returns the horizontal position of point, measured in columns, counting from 0 at the left margin. The column position is the sum of the widths of all the displayed representations of the characters between the start of the current line and point.
This function moves point to column in the current line. The calculation of column takes into account the widths of the displayed representations of the characters between the start of the line and point.
When called interactively, column is the value of prefix numeric argument. If column is not an integer, an error is signaled.
If it is impossible to move to column column because that is in
the middle of a multicolumn character such as a tab, point moves to the
end of that character. However, if force is non-
column is in the middle of a tab, then
either converts the tab into spaces (when
nil), or inserts enough spaces before it (otherwise), so that
point can move precisely to column column. Other multicolumn
characters can cause anomalies despite force, since there is no
way to split them.
The argument force also has an effect if the line isn’t long
enough to reach column column; if it is
t, that means to
add whitespace at the end of the line to reach that column.
The return value is the column number actually moved to.