INKEY

INKEY

Returns the last key-code in keyboard buffer, or an empty string if there are no keys. Special key-codes like the function-keys are returned as 2-byte string.

Example 1

WHILE(1)
  k = INKEY
  IF LEN(k)
    IF LEN(k)=2
      ? "H/W #"+ASC(RIGHT(k,1))
    ELSE
      ? k; " "; ASC(k)
    FI
  FI
  SHOWPAGE
WEND

Example 2

The following program will return the keycode and a string for every pressed key. The string can be used in an if-statement to querry if the key was pressed. See example 3 how to use the string.

while(1)
  k = INKEY

  if len(k)
    if len(k) == 2        
      print "2-Byte key code   : " + asc(mid(k,1,1)) + "  " + asc(mid(k,2,1));
      print " -> s = chr(";asc(mid(k,1,1));") + chr(";asc(mid(k,2,1));")" 
    else
      if(asc(k) > 37)
        print "Printable key code: "; asc(k); " -> s = \"";k;"\"" 
      else
        print "1-Byte key code   : "; asc(k);
        print " -> s = chr(";asc(k);")"
      endif
    endif
  endif
  
  showpage
wend

Example 3: Querry if a key was pressed

See example 2 to get the keycodes for the keys.

const KeyUp = chr(27) + chr(9)
const KeyDown = chr(27) + chr(10)
const KeySpace = " "
const KeyEsc = chr(27)
const KeyReturn = chr(13)

while(1)
  k = INKEY

  if len(k)
    select case k
        case KeyUp:     print "Up"
        case KeyDown:   print "Down"
        case KeySpace:  print "Space"
        case KeyEsc:    print "Esc"
        case KeyReturn: print "Return"
        case "a":       print "a"
        case "A":       print "A"
        case else:      print "other key"
    end select
  endif
  
  showpage
wend

Example 4: Input form

' Key values:
Const K_BKSP   = Chr(0x08)  ' BackSpace
Const K_TAB    = Chr(0x09)
Const K_ENTER  = Chr(0x0D)
Const K_ESC    = Chr(0x1B)  ' Escape
Const K_DELETE = Chr(0x7F)
Const K_PGUP   = K_ESC + Chr(0x01)  ' Page Up
Const K_PGDN   = K_ESC + Chr(0x02)  ' Page Down
Const K_LEFT   = K_ESC + Chr(0x04)  ' Arrow Left
Const K_RIGHT  = K_ESC + Chr(0x05)  ' Arrow Right
Const K_UP     = K_ESC + Chr(0x09)  ' Arrow Up
Const K_DOWN   = K_ESC + Chr(0x0A)  ' Arrow Down
Const K_INSERT = K_ESC + Chr(0x10)
Const K_HOME   = K_ESC + Chr(0x11)
Const K_END    = K_ESC + Chr(0x12)

' Edit string:
Def edit_char(txt, pos, char, ins_mode) = Replace(txt, pos, char, ins_mode = 0)
Def delete_char(txt, pos) = Replace(txt, pos, "", 1)

' Initialize three demo fields:
f_lbl = ["First Name:", "Last Name: ", "Your Hobby:"] ' field label
f_row = [3, 5, 7]     ' label row
f_col = [1, 1, 1]     ' label column
f_len = [10, 10, 20]  ' variable length
f_var = ["", "", ""]  ' variable value

' Index of fields:
Const MIN_IX = Lbound(f_lbl)
Const MAX_IX = Ubound(f_lbl)
ix = MIN_IX   ' Start on first field index
ins_mode = 1  ' Start in insert character mode

' Main demo loop:
While True
  ' Update variables:
  eol = Len(f_var(ix)) + 1                ' End Of Line
  If pos > eol Or pos < 1 Then pos = eol  ' Adjust cursor pos on new field
  ' Update screen:
  For i = MIN_IX To MAX_IX
    ' Print all fields:
    s  = Cat(0) + f_lbl(i) + " "
    s += Cat(3) + f_var(i) + Spc(f_len(i) - Len(f_var(i))) + " " ' + eol
    Locate f_row(i), f_col(i)
    Print s + Cat(0);
    ' Print the cursor:
    If i = ix Then
      If Not ins_mode Then Color 15
      Locate f_row(i), f_col(i) + Len(f_lbl(i)) + pos
      Print Cat(2) + Mid(f_var(i) + " ", pos, 1); ' (+ " " for eol)
    Fi
  Next i
  ' Update status line:
  s = "  (Esc=Stop)   |   " + Iff(ins_mode, "Insert ", "Replace") + Spc(3)
  s += Format("| 00:", ix) + Iff(pos = eol, "EOL", Format("000", pos)) + Spc(1)
  Locate 0, 0: Print Cat(0) + Cat(3) + s;
  Showpage ' SHOWPAGE makes INKEY works smoother (using SB 0.12.2)
  ' Wait for a key:
  Repeat: key = Inkey
  Until key <> ""
  ' Check key:
  Select Case key
  Case K_ESC:    Stop
  Case K_INSERT: ins_mode = Not ins_mode
  Case K_ENTER, K_TAB: ix++: If ix > MAX_IX Then ix = MIN_IX
  Case K_DOWN:   If ix < MAX_IX Then ix++
  Case K_UP:     If ix > MIN_IX Then ix--
  Case K_PGDN:   ix = MAX_IX
  Case K_PGUP:   ix = MIN_IX
  Case K_HOME:   pos = 1
  Case K_END:    pos = eol
  Case K_LEFT:   If pos > 1   Then pos--
  Case K_RIGHT:  If pos < eol Then pos++
  Case K_DELETE: If pos < eol Then f_var(ix) = delete_char(f_var(ix), pos)
  Case K_BKSP:   If pos > 1   Then pos--: f_var(ix) = delete_char(f_var(ix), pos)
  Case Else
    If Len(key) = 1 And Asc(key) >= 32 Then            ' Regular character?
      ins = ins_mode And (Len(f_var(ix)) < f_len(ix))  ' Insert mode
      rep = (Not ins_mode) And (pos <= f_len(ix))      ' Replace mode
      If ins Or rep Then
        f_var(ix) = edit_char(f_var(ix), pos, key, ins_mode)
        pos++  ' Move cursor to next character
      Fi
    Fi
  End Select
Wend

Example 5: A basic key code UNIT

REM Language:  SmallBASIC 0.12.6 (Linux 32-bit)
REM Purpose:   Special key values returned by INKEY.
REM            (Values returned by INKEY cannot be used for DEFINEKEY).
REM File name: key.bas
REM Unit name: key
REM Version:   1.0.0  24/05/2016
REM Author:    shian

' --- Start demo code ------------------------------------
'
'Import key
'
'? "Press Escape to stop..."
'Repeat: k = Inkey
'  Select Case k
'  Case Key.ENTER    : ? "Key.ENTER"
'  Case Key.TABK     : ? "Key.TABK"
'  Case Key.CLICK    : ? "Key.CLICK"
'  Case Key.FN(1)    : ? "Key.FN(1)"
'  Case Key.FN(12)   : ? "Key.FN(12)"
'  Case Key.CTRL("A"): ? "Key.CTRL(a)"
'  Case Key.ALT("A") : ? "Key.ALT(a)"
'  Case Key.CTRL(Key.Enter) : ? "Key.CTRL(Key.Enter)"
'  Case Key.ALT(Key.Enter)  : ? "Key.ALT(Key.Enter)"
'  Case Key.SHIFT(Key.Enter): ? "Key.SHIFT(Key.Enter)"
'  End Select
'Until k = Key.ESC
'
' --- End demo code ------------------------------------

Unit key

' Useful Constants:
Export BKSP, TABK, ENTER, ESC, BLANK, DEL
Export PGUP, PGDN, LEFTK, RIGHTK, UP, DOWN 
Export INS, HOMEK, ENDK, CLICK
' Useful Functions:
Export FN, CTRL, ALT, SHIFT
Export CTRL_ALT, ALT_SHIFT, CTRL_SHIFT  ' (used by system)
' The left character of INKEY (Useful only for special cases):
Export CTRL_CHR, ALT_CHR, SHIFT_CHR
Export CTRL_ALT_CHR, ALT_SHIFT_CHR, CTRL_SHIFT_CHR

Const CTRL_CHR       = Chr(0x01)    ' for Ctrl+Char
Const ALT_CHR        = Chr(0x02)    ' for Alt+Char
Const SHIFT_CHR      = Chr(0x03)    ' for Shift+Char
Const CTRL_ALT_CHR   = Chr(0x04)    ' for Ctrl+Alt+Char   (used by system)
Const ALT_SHIFT_CHR  = Chr(0x05)    ' for Alt+Shift+Char  (used by system)
Const CTRL_SHIFT_CHR = Chr(0x06)    ' for Ctrl+Shift+Char (used by system)
Const BKSP   = Chr(0x08)            ' BackSpace
Const TABK   = Chr(0x09)            ' Tab key
Const ENTER  = Chr(0x0D)
Const ESC    = Chr(0x1B)            ' Escape
Const BLANK  = Chr(0x20)            ' Space key
Const DEL    = Chr(0x7F)            ' Delete
Const PGUP   = ESC + Chr(0x01)      ' Page Up
Const PGDN   = ESC + Chr(0x02)      ' Page Down
Const LEFTK  = ESC + Chr(0x04)      ' Arrow Left key
Const RIGHTK = ESC + Chr(0x05)      ' Arrow Right key
Const UP     = ESC + Chr(0x09)      ' Arrow Up
Const DOWN   = ESC + Chr(0x0A)      ' Arrow Down
Const INS    = ESC + Chr(0x10)      ' Insert
Const HOMEK  = ESC + Chr(0x11)      ' Home key
Const ENDK   = ESC + Chr(0x12)      ' End key
Const CLICK  = ESC + Chr(0xC0)      ' Left Mouse Button Click
Def FN(n)    = ESC + Chr(0xF0 + n)  ' FN(1) is F1 (up to 12).
Def CTRL(c)  = CTRL_CHR  + Lcase(c) ' Ctrl+a, Ctrl+Enter, etc
Def ALT(c)   = ALT_CHR   + Lcase(c) ' Alt+a, Alt+Enter, etc
Def SHIFT(c) = SHIFT_CHR + c        ' Shift+Enter, Shift+Tab, etc

' These are system shortcuts - so it's advisable NOT to use them at all!
' (however, it's possible to detect them when not used by the system).
Def CTRL_ALT(c)   = CTRL_ALT_CHR   + Lcase(c)  ' Ctrl+Alt+a, etc
Def ALT_SHIFT(c)  = ALT_SHIFT_CHR  + Lcase(c)  ' Alt+Shift+a, etc
Def CTRL_SHIFT(c) = CTRL_SHIFT_CHR + Lcase(c)  ' Ctrl+Shift+a, etc

' ' Use this code to test and print key codes as hexa:
' ' --------------------------------------------------
' Print "Press Ctrl+B to stop..."
' While 1: k = Inkey: l = Len(k)
'   If l Then
'     ? "0x"; Right("00" + Hex(Asc(k)), 2);
'     If l = 2 Then ? Right("00" + Hex(Asc(Mid(k, 2))), 2);
'     Print
'   Fi
' Wend

AT BEEP CAT CLS DEFINEKEY FORM INKEY INPUT LINEINPUT LINPUT LOCATE LOGPRINT NOSOUND PEN PLAY PRINT SOUND TAB

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