A backspace key on a rock
Backspace← Backspace is the keyboard key that originally pushed the typewriter carriage one position backwards and in modern computer systems moves the display cursor one position backwards,[note 1] deletes the character at that position, and shifts back the text after that position by one position.
- Backspace ← Backspace is the keyboard key that originally pushed the typewriter carriage one position backwards and in modern computer systems moves the display cursor one position backwards, deletes the character at that position, and shifts back the text after that position by one position.
- Jun 24, 2014 Backspace Button in C# Submitted by donbermoy on Tuesday, June 24, 2014 - 21:36. We often click a backspace button in which this button is a keyboard key that display cursor one position backwards and deletes the character at that position, and shifts back the text after that position by one position.
- I've love to know how to echo a backspace in a batch file. For example: echo Deleting file. Del file.txt echo Done! Will give a two line result not including any result from the delete command.
- On a Macintosh, the backspace key is marked 'Delete' and performs the same function as the Windows-based backspace key (deletes the character to the left of the cursor). On a full-sized keyboard, the Windows backspace and Mac delete keys are both located in the top-right. Backspace Shortcuts.
Typewriter[edit]
A key combination can consist of a modifier key (such as CTRL, ALT, or SHIFT) and an accompanying key (such as a character key, an arrow key, a function key, and so on). After the user has chosen a key combination, the application retrieves the key combination from the hot key control and uses it to set up a hot key in the system.
In some[note 2] typewriters, a typist would, for example, type a lowercase letter A with acute accent (á) by typing a lowercase letter A, backspace, and then the acute accent key. This technique (also known as overstrike) is the basis for such spacing modifiers in computer character sets such as the ASCII caret (^, for the circumflex accent). Backspace composition no longer works with typical modern digital displays or typesetting systems[note 3] It has to some degree been replaced with the combining diacritical marks mechanism of Unicode, though such characters do not work well with many fonts, and precomposed characters continue to be used. Some software like TeX or Microsoft Windows use the opposite method for diacritical marks, namely positioning the accent first, and then the base letter on its position.
Computers[edit]
Although the term 'backspace' is the traditional name of the key which deletes the character to the left of the cursor, the actual key may be labeled in a variety of ways, for example delete,[1]Erase (for example in One Laptop Per Child),[2] or with a left pointing arrow.[3] A dedicated symbol for 'backspace' exists as U+232B ⌫ but its use as a keyboard label is not universal.
The backspace is distinct from the delete key, which in paper media for computers would punch out all the holes to strike out a character, and in modern computers deletes text following it. Also, the delete key often works as a generic command to remove an object (such as an image inside a document, or a file in a file manager), while backspace usually does not.[4][5][6]
Common use[edit]
In modern systems, the backspace key is often mapped to the delete character (0x7f in ASCII or Unicode), although the backspace key's function of deleting the character before the cursor remains.[3]
The backspace key is commonly used to go back a page or up one level in graphical web or file browsers.
^H[edit]
Pressing the backspace key on a computer terminal would generate the ASCII code 08, BS or Backspace, a control code which would delete the preceding character. That control code could also be accessed by pressing Control-H, as H is the eighth letter of the Latin alphabet. Terminals which did not have the backspace code mapped to the function of moving the cursor backwards and deleting the preceding character would display the symbols ^H (caret, H) when the backspace key was pressed. Even if a terminal did interpret backspace by deleting the preceding character, the system receiving the text might not. Then, the sender's screen would show a message without the supposedly deleted text, while that text, and the deletion codes, would be visible to the recipient. This sequence is still used humorously for epanorthosis by computer literates, denoting the deletion of a pretended blunder, much like a strikethrough; in this case, however, the ^H symbol is faked by typing a regular '^' followed by typing a regular 'H'.
Example:
- Be nice to this fool^H^H^H^Hgentleman; he's visiting from corporate HQ.[7]
^W and ^U[edit]
An alternative sometimes seen is ^W, which is the shortcut to delete the previous word in the Berkeley Unix terminal line discipline. This shortcut has also made it into the insert mode of the Vi text editor and its clone Vim.[8]
^U deletes a line.[9]
Other meanings[edit]
In a mainframe environment, to backspace means to move a magnetic tape backwards, typically to the previous block.
Notes[edit]
- ^'Backwards' means to the left for left-to-right languages.
- ^Many typewriters don't advance accent characters, so that no backspace is needed. However, it is still used e.g. for combining 'o' with '/'.
- ^There is no reason why a digital display or typesetting system could not be designed to allow backspace composition, a.k.a. overstrike, if an engineer chose to do that. As most contemporary computer display and typesetting systems are raster graphics-based rather than character-based (as of 2012), they make overstrike actually quite easy to implement. However, the use of proportional-width rather than fixed-width (monospaced) fonts makes the practical implementation of overstrike more complicated, and the original physical motivation for the technique is not present in digital computer systems.
IBM PC keyboard (Windows, US layout) | ||||||||||||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Esc | F1 | F2 | F3 | F4 | F5 | F6 | F7 | F8 | F9 | F10 | F11 | F12 | PrtScn/ SysRq | Scroll Lock | Pause/ Break | |||||||||
Insert | Home | PgUp | Num Lock | ∕ | ∗ | − | ||||||||||||||||||
Delete | End | PgDn | 7 | 8 | 9 | + | ||||||||||||||||||
4 | 5 | 6 | ||||||||||||||||||||||
↑ | 1 | 2 | 3 | Enter | ||||||||||||||||||||
← | ↓ | → | 0 Ins | . Del |
References[edit]
Look up backspace in Wiktionary, the free dictionary. |
Wikimedia Commons has media related to Backspace. |
- ^'User Mistakes or Mac Mistakes?, Backspace vs. Delete, and It's Too Easy to Zap an Icon in the Dock'. 2007.
- ^OLPC Wiki. 'OLPC Human Interface Guidelines/The Sugar Interface/Input Systems'. Archived from the original on 18 January 2008. Retrieved 2008-01-15.
- ^ ab'9.8 Keyboard configuration'. Debian Policy Manual. Archived from the original on 2016-03-10. Retrieved 2007-07-24.
- ^'Windows keyboard shortcuts overview'. Retrieved 2016-02-09.
- ^'Windows keyboard shortcuts overview'. Retrieved 2016-02-09.
- ^'Keyboard shortcuts for PCmanFM-QT [bug]/[Missing feature]'. Retrieved 2016-02-09.
- ^Chapter 5. Hacker Writing Style, The Jargon File, version 4.4.7
- ^'VIM USER MANUAL'. FreeBSD. November 2, 2013. Retrieved May 14, 2016.
- ^'FreeBSD Man Pages; vi'. Vimonline. March 9, 2002. Retrieved May 14, 2016.
Retrieved from 'https://en.wikipedia.org/w/index.php?title=Backspace&oldid=949546105'
-->What Key Combination Generates A Backspace Character In Cmd Key
A hot key control is a window that enables the user to enter a combination of keystrokes to be used as a hot key. A hot key is a key combination that the user can press to perform an action quickly. For example, a user can create a hot key that activates a given window and brings it to the top of the z-order. The hot key control displays the user's choices and ensures that the user selects a valid key combination. The following screen shot shows how a hot key control appears in a dialog box after the user presses the Alt key.
Using Hot Key Controls
When the user enters a key combination to be used as a hot key, the names of the keys appear in the hot key control. A key combination can consist of a modifier key (such as CTRL, ALT, or SHIFT) and an accompanying key (such as a character key, an arrow key, a function key, and so on).
After the user has chosen a key combination, the application retrieves the key combination from the hot key control and uses it to set up a hot key in the system. The information retrieved from the hot key control includes a flag indicating the modifier key and the virtual key code of the accompanying key.
The application can use the information provided by a hot key control to set up a global hot key or a thread-specific hot key. A global hot key is associated with a particular window; it allows the user to activate the window from any part of the system. An application sets a global hot key by using the WM_SETHOTKEY message. Whenever the user presses a global hot key, the window specified in WM_SETHOTKEY receives a WM_SYSCOMMAND message that specifies the SC_HOTKEY value. This message activates the window that receives it. The hot key remains valid until the application that called WM_SETHOTKEY exits.
A thread-specific hot key generates a WM_HOTKEY message that is posted to the beginning of a particular thread so that it is removed by the next iteration of the message loop. An application sets a thread-specific hot key by using the RegisterHotKey function.
Hot Key Control Messages
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After creating a hot key control, an application interacts with it by using three messages: HKM_SETRULES, HKM_SETHOTKEY, and HKM_GETHOTKEY.
An application can send the HKM_SETRULES message to specify a set of CTRL, ALT, and SHIFT key combinations that are considered invalid hot keys. If the application specifies an invalid key combination, it should also specify a default modifier combination to use when the user selects the invalid combination. When the user enters the invalid combination, the system performs a logical OR operation on the invalid combination and the default combination. The result is considered a valid combination; it is converted to a string and displayed in the control.
The HKM_SETHOTKEY message allows an application to set the hot key combination for a hot key control. This message is also typically used when the hot key control is created.
Applications use the HKM_GETHOTKEY message to retrieve the virtual key code and modifier flags of the hot key chosen by the user.
Hot Key Control Notifications
The hot key control does not send any notification codes via the WM_NOTIFY message. It will, however, send the EN_CHANGE notification via the WM_COMMAND message when the user changes the contents of the control.
What Key Combination Generates A Backspace Character In Cmd Windows 10
Default Hot Key Message Processing
What Key Combination Generates A Backspace Character In Cmd Download
This section describes the window messages handled by the window procedure for the pre defined HOTKEY_CLASS window class used with hot key controls.
Message | Processing performed |
WM_CHAR | Retrieves the virtual key code. |
WM_CREATE | Initializes the hot key control, clears any hot key rules, and uses the system font. |
WM_ERASEBKGND | Hides the caret, calls the DefWindowProc function, and shows the caret again. |
WM_GETDLGCODE | Returns a combination of the DLGC_WANTCHARS and DLGC_WANTARROWS values. |
WM_GETFONT | Retrieves the font. |
WM_KEYDOWN | Calls the DefWindowProc function if the key is ENTER, TAB, SPACE BAR, DEL, ESC, or BACKSPACE. If the key is SHIFT, CTRL, or ALT, it checks whether the combination is valid and, if it is, sets the hot key using the combination. All other keys are set as hot keys without their validity being checked first. |
WM_KEYUP | Retrieves the virtual key code. |
WM_KILLFOCUS | Destroys the caret. |
WM_LBUTTONDOWN | Sets the focus to the window. |
WM_NCCREATE | Sets the WS_EX_CLIENTEDGE window style. |
WM_PAINT | Paints the hot key control. |
WM_SETFOCUS | Creates and shows the caret. |
WM_SETFONT | Sets the font. |
WM_SYSCHAR | Retrieves the virtual key code. |
WM_SYSKEYDOWN | Calls the DefWindowProc function if the key is ENTER, TAB, SPACE BAR, DEL, ESC, or BACKSPACE. If the key is SHIFT, CTRL, or ALT, it checks whether the combination is valid and, if it is, sets the hot key using the combination. All other keys are set as hot keys without their validity being checked first. |
WM_SYSKEYUP | Retrieves the virtual key code. |