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.
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.
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.
command move-to-column column \&optional force
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
move-to-column 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.
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.