Carriage return
From Wikipedia, the free encyclopedia
Originally, carriage return was the term for the lever or mechanism on a typewriter that would cause the cylinder on which the paper was held (the carriage) to return to the left side of the paper after a line of text had been typed, and would usually move the paper to the next line as well. The first power carriage return was added to electric typewriters by Smith Corona in 1960. The key for this was usually labelled "carriage return" or "return". To improve the keyboard for non-English-speakers, the symbol ↵ was introduced to mark this key, since this graphic could communicate the action of the key without using words.
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[edit] Computer analogues
In computing, the carriage return (CR) is one of the control characters in ASCII code, Unicode or EBCDIC that commands a printer or other sort of display to move the position of the cursor to the first position on the same line. It was mostly used along with line feed, a move to the next line, while carriage return precedes line feed to indicate a new line. The term derives from the above usage, as early printers often closely resembled typewriters; this control character would activate a physical carriage-return mechanism.
Many computer programs use the carriage return character, alone or with a line feed, to signal the end of a line of text, but other characters are also used for this function (see newline); others use it only for a paragraph break (a hard return).
In ASCII and Unicode, the character code decimal 13 (or hexadecimal 0D) is defined to be carriage return.
Some standards (for example HTML) treat carriage return and its relative line feed as whitespace.
In the C programming language and many other languages influenced by it, \r denotes this character.
Though used interchangebly today, the Return key and Enter key actually send different scan code, so can be programmed for different uses.
[edit] User interface functionality
On Windows, Macintosh and most other GUI operating systems, hitting the return key also results in the default option of a dialog box (usually OK or Yes) being selected.
[edit] Summary
- Keys commonly generating the character "carriage return":
- "Enter" key
- "Return" key
- ↵ key
- Control-M
- ASCII and Unicode representation of "carriage return":
- Decimal code: 13
- Hexadecimal code: 0D
- Mnemonic symbol: CR
- Programming
- Php, Python, Bash, C/C++, Java, Javascript, Perl: \r
- Visual Basic .NET: _
[edit] See also
| Computer Keyboard Keys | |
|---|---|
| Dead keys | Compose |
| Modifier keys | Control · Shift · Alt/Option (Apple) · AltGr · Command/Meta (MIT keyboards) · Windows · Fn (compact keyboards) |
| Lock keys | Scroll lock · Num lock · Caps lock · Shift key |
| Navigation | Arrow · Page scrolling (Page up/Page down) · Home/End |
| Editing | Return/Enter · Backspace · Insert · Delete · Tab · Space bar |
| Misc. | SysRq/Print screen · Break/Pause · Escape · Menu · Numeric keypad · Function · Power management (Power, Sleep, Wake) · Language input |
