Text editor

A text editor is a type of computer program that edits plain text. Such programs are sometimes known as "notepad" software (e.g. Windows Notepad).^[1][2][3] Text editors are provided with operating systems and software development packages, and can be used to change files such as configuration files, documentation files and programming language source code.^[4]

Plain text and rich text

There are important differences between plain text (created and edited by text editors) and

Plain text exclusively consists of character representation. Each character is represented by a fixed-length sequence of one, two, or four bytes, or as a variable-length sequence of one to four bytes, in accordance to specific

Rich text, on the other hand, may contain metadata, character formatting data (e.g.

The first interactive text editors were "line editors" oriented to teleprinter- or typewriter-style terminals without displays. Commands (often a single keystroke) effected edits to a file at an imaginary insertion point called the "cursor". Edits were verified by typing a command to print a small section of the file, and periodically by printing the entire file. In some line editors, the cursor could be moved by commands that specified the line number in the file, text strings (context) for which to search, and eventually regular expressions. Line editors were major improvements over keypunching. Some line editors could be used by keypunch; editing commands could be taken from a deck of cards and applied to a specified file. Some common line editors supported a "verify" mode in which change commands displayed the altered lines.

When

The core data structure in a text editor is the one that manages the string (sequence of characters) or list of records that represents the current state of the file being edited. While the former could be stored in a single long consecutive

Types of text editors

Some text editors are small and simple, while others offer broad and complex functions. For example,

Most word processors can read and write files in plain text format, allowing them to open files saved from text editors. Saving these files from a word processor, however, requires ensuring the file is written in

• Find and replace – Text editors provide extensive facilities for searching and replacing strings of text, either individually, or groups of files in opened tabs or a selected folder. Advanced editors can use
  better source needed
  ]
• Cut, copy, and paste – most text editors provide methods to duplicate and move text within the file, or between files.
• Ability to handle UTF-8 encoded text.
• bullet list formatting using ASCII characters, comment formatting, syntax highlighting
  and so on. These are typically only for display and do not insert formatting codes into the file itself.
• Undo and redo – As with word processors, text editors provide a way to undo and redo the last edit, or more. Often—especially with older text editors—there is only one level of edit history remembered and successively issuing the undo command will only "toggle" the last change. Modern or more complex editors usually provide a multiple-level history such that issuing the undo command repeatedly will revert the document to successively older edits. A separate redo command will cycle the edits "forward" toward the most recent changes. The number of changes remembered depends upon the editor and is often configurable by the user.
• Ability to jump to a specified line number.^{[citation needed]}

Advanced features

• Macro or procedure definition: to define new commands or features as combinations of prior commands or other macros, perhaps with passed parameters, or with nesting of macros.
• Profiles to retain options set by the user between editing session.
• Profile macros with names specified in, e.g., environment, profile, executed automatically at the beginning of an edit session or when opening a new file.
• Multi-file editing: the ability to edit multiple files during an edit-session, perhaps remembering the current-line cursor of each file, to insert repeated text into each file, copy or move text among files, compare files side-by-side (perhaps with a tiled multiple-document interface), etc.
• Multi-view editors: the ability to display multiple views of the same file, with independent cursor tracking, synchronizing changes among the windows but providing the same facilities as are available for independent files.
• Collapse/expand, also called folding: the ability to temporarily exclude sections of the text from view. This may either be based on a range of line numbers or on some syntactic element, e.g., excluding everything between a BEGIN; and the matching END;.
• Column-based editing; the ability to alter or insert data at a particular column, or to shift data to specific columns.
• shell
  . Also, a case-shifting feature could translate to lowercase or uppercase.
• Filtering – Some advanced text editors allow the editor to send all or sections of the file being edited to another utility and read the result back into the file in place of the lines being "filtered". This, for example, is useful for sorting a series of lines alphabetically or numerically, doing mathematical computations, indenting source code, and so on.
• config files and other text that appears in an organized or predictable format. Editors generally allow users to customize the colors or styles used for each language element. Some text editors also allow users to install and use themes to change the look and feel of the editor's entire user interface
  .
• Syntax-oriented editors - some editors have support for the syntax of one or more languages, and allow operations in terms of syntactical unit, e.g., insert a new WHEN clause in a SELECT statement.
• coding styles
  .
• Block-oriented terminals
  typically have dedicated cursor movement keys, as do keyboards on personal computers.
• Command line - some editors, e.g., ISPF, XEDIT, have a dedicated field on the screen for entering commands as opposed to text. Depending on the editor, the user may have to use cursor keys to switch between the command and text fields or the editor may interpret, e.g., specific function keys , as requests to switch.
• Line commands, also known as prefix commands or sequence commands - Some editors treat a file as an array of text lines with associated line numbers or sequence numbers, and have a distinct line number field for each text field. A line command is a string that the user types into a line number field and that the editor recognizes as a command operating on that specific line or block of lines, e.g., LC to translate a line to lower case, ))3 to shift a block right three columns. Some editors also support line macros, also known as prefix macros or sequence macros. Despite the name prefix command, some editors allow the sequence field to appear after the text field.
• Text editors, especially source-code editors, often default to using a monospace font that clearly distinguishes between similar characters (homoglyphs) such as the colon and the semicolon.^[19]

Specialised editors

Some editors include special features and extra functions, for instance,

• Source code editors are text editors with additional functionality to facilitate the production of source code. These often feature user-programmable syntax highlighting and code navigation functions as well as coding tools or keyboard macros
  similar to an HTML editor.
• Folding editors
  . This subclass includes so-called "orthodox editors" that are derivatives of Xedit. Editors that implement folding without programing-specific features are usually called outliners (see below).
• IDEs (integrated development environments) are designed to manage and streamline large programming projects. They are usually only used for programming as they contain many features unnecessary for simple text editing.
• template files
  that are assembled by the software controlling the site and do not compose a complete HTML document.
• Mathematicians, physicists, and computer scientists often produce articles and books using TeX or LaTeX in plain text files. Such documents are often produced by a standard text editor, but some people use specialized TeX editors.
• Outliners. Also called tree-based editors, because they combine a hierarchical outline tree with a text editor. Folding (see above) can be considered a specialized form of outlining.
• Collaborative editors allow multiple users to work on the same document simultaneously from remote locations over a network. The changes made by individual users are tracked and merged into the document automatically to eliminate the possibility of conflicting edits. These editors also typically include an online chat
  component for discussion among editors.
• notification area
  .

Programmable editors can usually be enhanced to perform any or all of these functions, but simpler editors focus on just one, or, like gPHPedit, are targeted at a single programming language.

See also

Notes