Text editor functions

Answer 1

Text editors allow data entry and updating. Some additional capabilities are:
- duplicating or deleting lines or blocks of lines
- changing specific text or using a regular expression to change a range of text
- moving sections of text
- finding text
- screen movement (up, down, left or right) by line, page or top/bottom
- command retrieval and repetition
- a macro facility
- retrieval of other files into the current one
- sorting
- regular expression capability
- undoing changes
- allowing more than one file to be edited at the same time
- writing to, appending to, or clearing the clipboard
- filling or overlaying areas with numbers or text
- splitting and joining lines either manually or at/after some text
- allowing split screens on the same or different files
- allowing invocation of external code/applications
- setting and going to bookmarks (in larger files)
- centering or justifying text
- excluding lines not of interest
- formatting or justifying paragraphs in various ways
- showing changed lines
- randomizing lines or paragraphs
- highlighting keywords or entire lines
- aligning strings within lines
- showing duplicate or unique data
- counting words or strings

Many text editors have these functions built in, other can be extended via
the macro facility. Emacs, SlickEdit, UltraEdit and VIM are extremely powerful
but require time and effort to master.