15 |
often speak of the character ``at'' a position, meaning the character |
often speak of the character ``at'' a position, meaning the character |
16 |
after that position. |
after that position. |
17 |
|
|
18 |
Positions are usually represented as integers starting from 1, but can |
Positions are usually represented as integers starting from 1, but |
19 |
also be represented as @dfn{markers}---special objects that relocate |
can also be represented as @dfn{markers}---special objects that |
20 |
automatically when text is inserted or deleted so they stay with the |
relocate automatically when text is inserted or deleted so they stay |
21 |
surrounding characters. Functions that expect an argument to be a |
with the surrounding characters. Functions that expect an argument to |
22 |
position (an integer), but accept a marker as a substitute, normally |
be a position (an integer), but accept a marker as a substitute, |
23 |
ignore the marker buffer. Of course, markers used this way usually |
normally ignore which buffer the marker points into; they convert the |
24 |
point to a position in the buffer that the function operates on, but |
marker to an integer, and use that integer, exactly as if you had |
25 |
that is entirely the programmer's responsibility. @xref{Markers}. |
passed the integer as the argument. Markers used this way usually |
26 |
|
point to a position in the buffer that the function will operate on, |
27 |
|
but if not, they are converted to integers anyway. @xref{Markers}. |
28 |
|
|
29 |
See also the ``field'' feature (@pxref{Fields}), which provides |
See also the ``field'' feature (@pxref{Fields}), which provides |
30 |
functions that are used by many cursor-motion commands. |
functions that are used by many cursor-motion commands. |