A particularly easy way to move the cursor is accomplished by using the
command line. Since you have not learned so far how to
issue command line commands, we will briefly outline here the
general format of how it is done.
The general procedure for issuing a command line command is very
straightforward. We summarize it below:
- Press <Esc> to move the cursor down to the command line
- Enter the command
- Press <Return> to execute the command
To return to our demonstration of moving the cursor by
this method, note that we can move the cursor to any line desired simply by
entering the line number as a command:
- Press <Esc> to bring the cursor to the command line
- Type the number 2
- Press <Return>
Now the cursor will position itself at the beginning of line 2.
Programmers will find this feature very useful in debugging programs,
since the error message of a compiler usually indicates in which line
the error is located.
Column commands can also be entered in this way.
To tell the cursor to go to a specific row and column, type the row
number and then the column number with a comma in between:
- Press <Esc>
- Type `2,6'
- Press <Return>
This sequence moves the cursor to line 2 and column 6. Notice that with
regard to the column number, the command is able to place the cursor in
virtual territory. This is not true for line numbers. To test
this, try issuing a command to move the cursor to line 12.
If you omit the line number entirely and just type, for example, the
command `,6', the cursor will be placed in column 6 of
whatever row it finds itself.
If you want to find out the location of the cursor, follow
the same procedure using the `=' command.
- Press <Esc>
- Type `='
- Press <Return>
The column the cursor is in will be displayed just after the
`:' symbol in the command line, followed by information about
the position of the cursor relative to the end of the file as well as
its precise location on the screen. For example, in our case, with the
cursor on line 2 and in column 6, something like the following will
appear on the command line (the number of bytes varies depending on how
many tabs and spaces you may have typed):
![\fbox{\makebox[12cm]{\tt 2 : 6 bytes=25/78
screen=2,6\hfill IA$\infty $NY B1${}^{\cdot} $HELLO.C }}](img4.png)
Now let's make use of the '=' command to learn more about how
virtual space is counted.
- move the cursor around on the screen,
occasionally giving the `=' command to see where the cursor is.
You will see that although virtual lines are not counted in the
information displayed, virtual spaces are included in the column count. This combination is most natural for programming since
one often needs to know the line number of a particular line; at the
same time, certain languages (notably Fortran) are column-dependent,
hence one must know which column the cursor is in and whether it is in
virtual territory or not.
Command line commands for cursor movement
| Action Desired |
Command to Use |
| Move cursor to line desired |
Type line # |
| Move cursor to row and column |
Row #,Column # |
| Move cursor to column on the |
,Column # |
| same row |
|
| Find location of cursor |
Type = |