CLEAR TYPEAHEAD

CLEAR TYPEAHEAD

Empty the keyboard buffer

Syntax

      CLEAR TYPEAHEAD

Description

CLEAR TYPEAHEAD is a keyboard command that clears all pending keys from the Clipper keyboard buffer. This is useful in user interface procedures or user-defined functions to guarantee that keys processed from the keyboard buffer are appropriate to the current activity and not pending from a previous activity. User functions called by ACHOICE() and DBEDIT() are especially sensitive to such keys.

Note that both the SET TYPEAHEAD and KEYBOARD commands also clear the keyboard buffer.

Examples

      .  This example empties the keyboard buffer before invoking
      DBEDIT(), guaranteeing that any pending keys will not be executed:
      CLEAR TYPEAHEAD
      DBEDIT()

Seealso

KEYBOARD, SET TYPEAHEAD

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CLEAR GETS

CLEAR GETS

Release Get objects from the current GetList array

Syntax

       CLEAR GETS

Description

CLEAR GETS explicitly releases all Get objects in the current and visible GetList array, and terminates the calling READ, releasing any remaining objects in the calling READ, if executed within a SET KEY procedure or a user-defined function invoked by a VALID clause. CLEAR GETS releases Get objects by assigning an empty array to the variable GetList. GetList is the name of the variable used to hold an array of Get objects for subsequent READ commands. There are two other mechanisms that automatically release Get objects: CLEAR specified without the SCREEN clause, and READ specified without the SAVE clause.

CLEAR GETS has two basic uses. First, it can be used to terminate a READ from a SET KEY procedure or VALID user-defined function. Second, it can be used to delete Get objects from the GetList array when you have not executed a READ or you have saved the Get objects by using READ SAVE.

Seealso

@…CLEAR, @…GET, CLOSE, READ, RELEASE, SET TYPEAHEAD

SetTypeahead()

SetTypeahead()

Sets the typeahead buffer to given size.

Syntax

      SetTypeahead( <nSize> ) --> <nPreviousSize>

Arguments

<nSize> is a valid typeahead size.

Returns

<nPreviousSize> The previous state of _SET_TYPEAHEAD

Description

This function sets the typeahead buffer to a valid given size as is Set(_SET_TYPEAHEAD) where used.

Examples

      // Sets typeahead to 12
      SetTypeahead( 12 )

Compliance

Clipper

Files

Library is core

Seealso

__Accept(), __Input()

C5 UI General

 

C5 UI General :

CLEAR TYPEAHEAD :

Empty the keyboard buffer

CLEAR TYPEAHEAD

INKEY() :

Extract a character from the keyboard buffer

 
INKEY( [ <nSeconds> ] ) --> nInkeyCode

KEYBOARD :

Stuff a string into the keyboard buffer

KEYBOARD <cString>

LASTKEY() :

Return the INKEY() value of the last key in the buffer

LASTKEY() --> nInkeyCode

NEXTKEY() :

Read the pending key in the keyboard buffer

NEXTKEY() --> nInkeyCode

SET TYPEAHEAD :

Set the size of the keyboard buffer

SET TYPEAHEAD TO <nKeyboardSize>

 

 

C5_SET TYPEAHEAD

SET TYPEAHEAD
 Set the size of the keyboard buffer
------------------------------------------------------------------------------
 Syntax

     SET TYPEAHEAD TO <nKeyboardSize>

 Arguments

     TO <nKeyboardSize> specifies the number of keystrokes the keyboard
     buffer can hold from a minimum of zero to a maximum of 4096.  The
     default size of the keyboard buffer is machine-dependent but 16 is the
     minimum size.

 Description

     SET TYPEAHEAD defines the size of the Clipper keyboard buffer that
     caches keystrokes input directly by the user.  SET TYPEAHEAD, however,
     does not affect the number of characters that can be stuffed
     programmatically using the KEYBOARD command.  When executed, SET
     TYPEAHEAD clears the keyboard buffer and sets the size to
     <nKeyboardSize>.

     When TYPEAHEAD is SET TO zero, keyboard polling is suspended.  An
     explicit request for keyboard input, however, will temporarily enable
     the keyboard and read any pending keystrokes from the BIOS buffer.
     Calling NEXTKEY() constitutes such an explicit request.  NEXTKEY() reads
     any pending keystrokes from the BIOS buffer and returns the INKEY()
     value of the first keystroke read, or zero if no keystrokes are pending.

 Files   Library is CLIPPER.LIB.

See Also: ALTD() CLEAR TYPEAHEAD INKEY() KEYBOARD NEXTKEY()



C5 Commands

 ?|??            Display one or more values to the console
 @...BOX         Draw a box on the screen
 @...CLEAR       Clear a rectangular region of the screen
 @...GET         Create a new Get object and display it
 @...PROMPT      Paint a menu item and define a message
 @...SAY         Display data at a specified screen or printer row and column
 @...TO          Draw a single- or double-line box
 ACCEPT*         Place keyboard input into a memory variable
 APPEND BLANK    Add a new record to the current database file
 APPEND FROM     Import records from a database (.dbf) file or ASCII text file
 AVERAGE         Average numeric expressions in the current work area
 CALL*           Execute a C or Assembler procedure
 CANCEL*         Terminate program processing
 CLEAR ALL*      Close files and release public and private variables
 CLEAR GETS      Release Get objects from the current GetList array
 CLEAR MEMORY    Release all public and private variables
 CLEAR SCREEN    Clear the screen and return the cursor home
 CLEAR TYPEAHEAD Empty the keyboard buffer
 CLOSE           Close a specific set of files
 COMMIT          Perform a solid-disk write for all active work areas
 CONTINUE        Resume a pending LOCATE
 COPY FILE       Copy a file to a new file or to a device
 COPY STRUCTURE  Copy the current .dbf structure to a new database (.dbf) file
 COPY STRU EXTE  Copy field definitions to a .dbf file
 COPY TO         Export records to a database (.dbf) file or ASCII text file
 COUNT           Tally records to a variable
 CREATE          Create an empty structure extended (.dbf) file
 CREATE FROM     Create a new .dbf file from a structure extended file
 DELETE          Mark records for deletion
 DELETE FILE     Remove a file from disk
 DELETE TAG      Delete a tag
 DIR*            Display a listing of files from a specified path
 DISPLAY         Display records to the console
 EJECT           Advance the printhead to top of form
 ERASE           Remove a file from disk
 FIND*           Search an index for a specified key value
 GO              Move the pointer to the specified identity
 INDEX           Create an index file
 INPUT*          Enter the result of an expression into a variable
 JOIN            Create a new database file by merging from two work areas
 KEYBOARD        Stuff a string into the keyboard buffer
 LABEL FORM      Display labels to the console
 LIST            List records to the console
 LOCATE          Search sequentially for a record matching a condition
 MENU TO         Execute a lightbar menu for defined PROMPTs
 NOTE*           Place a single-line comment in a program file
 PACK            Remove deleted records from a database file
 QUIT            Terminate program processing
 READ            Activate full-screen editing mode using Get objects
 RECALL          Restore records marked for deletion
 REINDEX         Rebuild open indexes in the current work area
 RELEASE         Delete public and private memory variables
 RENAME          Change the name of a file
 REPLACE         Assign new values to field variables
 REPORT FORM     Display a report to the console
 RESTORE         Retrieve memory variables from a memory (.mem) file
 RESTORE SCREEN* Display a saved screen
 RUN             Execute a DOS command or program
 SAVE            Save variables to a memory (.mem) file
 SAVE SCREEN*    Save the current screen to a buffer or variable
 SEEK            Search an order for a specified key value
 SELECT          Change the current work area
 SET ALTERNATE   Echo console output to a text file
 SET BELL        Toggle sounding of the bell during full-screen operations
 SET CENTURY     Modify the date format to include or omit century digits
 SET COLOR*      Define screen colors
 SET CONFIRM     Toggle required exit key to terminate GETs
 SET CONSOLE     Toggle console display to the screen
 SET CURSOR      Toggle the screen cursor on or off
 SET DATE        Set the date format for input and display
 SET DECIMALS    Set the number of decimal places to be displayed
 SET DEFAULT     Set the CA-Clipper default drive and directory
 SET DELETED     Toggle filtering of deleted records
 SET DELIMITERS  Toggle or define GET delimiters
 SET DESCENDING  Change the descending flag of the controlling order
 SET DEVICE      Direct @...SAYs to the screen or printer
 SET EPOCH       Control the interpretation of dates with no century digits
 SET ESCAPE      Toggle Esc as a READ exit key
 SET EXACT*      Toggle exact matches for character strings
 SET EXCLUSIVE*  Establish shared or exclusive USE of database files
 SET FILTER      Hide records not meeting a condition
 SET FIXED       Toggle fixing of the number of decimal digits displayed
 SET FORMAT*     Activate a format when READ is executed
 SET FUNCTION    Assign a character string to a function key
 SET INDEX       Open one or more order bags in the current work area
 SET INTENSITY   Toggle enhanced display of GETs and PROMPTs
 SET KEY         Assign a procedure invocation to a key
 SET MARGIN      Set the page offset for all printed output
 SET MEMOBLOCK   Change the block size for memo files
 SET MESSAGE     Set the @...PROMPT message line row
 SET OPTIMIZE    Change the setting that optimizes using open orders
 SET ORDER       Select the controlling order
 SET PATH        Specify the CA-Clipper search path for opening files
 SET PRINTER     Toggle echo of output to printer or set the print destination
 SET PROCEDURE*  Compile procedures and functions into the current object file
 SET RELATION    Relate two work areas by a key value or record number
 SET SCOPE       Change the boundaries for scoping keys in controlling order
 SET SCOPEBOTTOM Change bottom boundary for scoping keys in controlling order
 SET SCOPETOP    Change top boundary for scoping keys in controlling order
 SET SCOREBOARD  Toggle the message display from READ or MEMOEDIT()
 SET SOFTSEEK    Toggle relative seeking
 SET TYPEAHEAD   Set the size of the keyboard buffer
 SET UNIQUE*     Toggle inclusion of non-unique keys into an index
 SET WRAP*       Toggle wrapping of the highlight in menus
 SKIP            Move the record pointer to a new position
 SORT            Copy to a database (.dbf) file in sorted order
 STORE*          Assign a value to one or more variables
 SUM             Sum numeric expressions and assign results to variables
 TEXT*           Display a literal block of text
 TOTAL           Summarize records by key value to a database (.dbf) file
 TYPE            Display the contents of a text file
 UNLOCK          Release file/record locks set by the current user
 UPDATE          Update current database file from another database file
 USE             Open an existing database (.dbf) and its associated files
 WAIT*           Suspend program processing until a key is pressed
 ZAP             Remove all records from the current database file

 

C5 Environment Commands and Functions

Commands :

SET BELL :

Toggle automatic sounding of the bell during full-screen operations

SET BELL on | OFF | <xlToggle>

SET COLOR :

Define screen colors

SET COLOR | COLOUR TO [ [<standard>]
    [, <enhanced>] [, <border>] [, <background> ]
    [, <unselected>]] | ( <cColorString> )

SET DEFAULT :

Set the default drive and directory

SET DEFAULT TO [ <xcPathspec> ]

SET FUNCTION :

Assign a character string to a function key

SET FUNCTION <nFunctionKey> TO <cString>

SET TYPEAHEAD :

Set the size of the keyboard buffer

SET TYPEAHEAD TO <nKeyboardSize>

Functions :

CURDIR() :

Return the current DOS directory

CURDIR( [ <cDrivespec> ] ) --> cDirectory

DISKSPACE() :

Return the space available on a specified disk

DISKSPACE( [ <nDrive> ] ) --> nBytes

FKLABEL()* :

Return function key name

FKLABEL( <nFunctionKey> ) --> cKeyLabel

FKMAX()* :

Return number of function keys as a constant

FKMAX() --> nFunctionKeys

GETENV() :

Retrieve the contents of a DOS environment variable

GETENV( <cEnvironmentVariable> ) --> cString

ISCOLOR() :

Determine if the current computer has color compatibility

ISCOLOR() | ISCOLOUR() --> lBoolean

MAXROW() :

Determine the maximum visible screen row

MAXROW() --> nRow

MAXCOL() :

Determine the maximum visible screen column

MAXCOL() --> nColumn

MEMORY() :

Determine the amount of available free pool memory

MEMORY( <nMemoryType> ) --> nKbytes

NOSNOW() :

Toggle snow position

NOSNOW( <lToggle> ) --> NIL

OS() :

Return the operating system name

OS() --> cOSName

SET() :

Inspect or change a global setting

SET( <nSpecifier>, [<expNewSetting>], [<lOpenMode> ] )
      --> CurrentSetting

TONE() :

Sound a speaker tone for a specified frequency and duration

TONE( <nFrequency>, <nDuration> ) --> NIL

VERSION() :

Returns Clipper Compiler version

VERSION() --> cVersion