32. Text

This chapter describes the functions that deal with the text in a buffer. Most examine, insert, or delete text in the current buffer, often operating at point or on text adjacent to point. Many are interactive. All the functions that change the text provide for undoing the changes (see section 32.9 Undo).

Many text-related functions operate on a region of text defined by two buffer positions passed in arguments named start and end. These arguments should be either markers (see section 31. Markers) or numeric character positions (see section 30. Positions). The order of these arguments does not matter; it is all right for start to be the end of the region and end the beginning. For example, (delete-region 1 10) and (delete-region 10 1) are equivalent. An args-out-of-range error is signaled if either start or end is outside the accessible portion of the buffer. In an interactive call, point and the mark are used for these arguments.

Throughout this chapter, "text" refers to the characters in the buffer, together with their properties (when relevant). Keep in mind that point is always between two characters, and the cursor appears on the character after point.

32.1 Examining Text Near Point		Examining text in the vicinity of point.
32.2 Examining Buffer Contents		Examining text in a general fashion.
32.3 Comparing Text		Comparing substrings of buffers.
32.4 Inserting Text		Adding new text to a buffer.
32.5 User-Level Insertion Commands		User-level commands to insert text.
32.6 Deleting Text		Removing text from a buffer.
32.7 User-Level Deletion Commands		User-level commands to delete text.
32.8 The Kill Ring		Where removed text sometimes is saved for later use.
32.9 Undo		Undoing changes to the text of a buffer.
32.10 Maintaining Undo Lists		How to enable and disable undo information. How to control how much information is kept.
32.11 Filling		Functions for explicit filling.
32.12 Margins for Filling		How to specify margins for filling commands.
32.13 Adaptive Fill Mode		Adaptive Fill mode chooses a fill prefix from context.
32.14 Auto Filling		How auto-fill mode is implemented to break lines.
32.15 Sorting Text		Functions for sorting parts of the buffer.
32.16 Counting Columns		Computing horizontal positions, and using them.
32.17 Indentation		Functions to insert or adjust indentation.
32.18 Case Changes		Case conversion of parts of the buffer.
32.19 Text Properties		Assigning Lisp property lists to text characters.
32.20 Substituting for a Character Code		Replacing a given character wherever it appears.
32.22 Transposition of Text		Swapping two portions of a buffer.
32.21 Registers		How registers are implemented. Accessing the text or position stored in a register.
32.23 Base 64 Encoding		Conversion to or from base 64 encoding.
32.24 MD5 Checksum		Compute the MD5 "message digest"/"checksum".
32.25 Change Hooks		Supplying functions to be run when text is changed.