Task

Clear the terminal window.

11l

Translation of: Python

To clear the screen on Windows, replace 'clear' with 'cls' <lang 11l>os:(‘clear’)</lang>

6502 Assembly

Works with: [VICE]

This example has been written for the C64 and uses the CHROUT KERNEL routine. Compile with the Turbo Macro Pro cross assembler:

tmpx -i clrscr.s -o bin/clrscr.prg

Run with:

SYS680

<lang 6502asm>; C64 - Terminal control: Clear the screen

*** labels ***

chrout = $ffd2

*** main ***

               *=$02a8         ; sys 680
               
               lda clr         ; A = {CLR}
               jsr chrout      ; Output a character in A to the current
                               ; output device (default: screen).
               rts

*** data ***

clr .byte $93 ; the CLR control code

                               ; see https://en.wikipedia.org/wiki/PETSCII

</lang>

Works with: [6502asm.com] version 1.2

Works with: [6502asm.com] version 1.5 beta

The 6502asm.com emulator has a 32x32 pixel screen. First we fill this screen with random colored pixels, wait for a keypress and then "clear" the screen (fill it with black pixels). <lang 6502asm>; 6502asm.com - Clear the screen

               lda #$00        ; store the start address of the screen ($200)
               sta $00         ; at $00 and $01 (high byte in $01)
               lda #$02
               sta $01
               
               ldy #$00        ; Y = 0

fillscreen:

               lda $fe         ; A = random number from $fe
               sta ($00),y     ; put pixel (random color) to the screen
               iny             ; Y++
               bne fillscreen  ; loop if Y!=0
               inc $01         ; increase address high byte
               lda $01
               cmp #$06        ; A==6? (screen ends at $05ff)
               bne fillscreen  ; no -> loop

waitforkeypress:

               lda $ff         ; $ff is 0 if no key has been pressed
               beq waitforkeypress
               
               ldx #$00
               lda #$00        ; black

clearscreen:

               sta $0200,x
               sta $0300,x
               sta $0400,x
               sta $0500,x
               inx
               bne clearscreen

</lang>

8080 Assembly

On almost all video terminals, from the earliest ones to today's terminal emulators, sending an ASCII Form Feed control character (code 12) will clear the screen.

This program uses a CP/M system call to send a Form Feed character to the standard output, as CP/M was the de facto standard operating system for 8080-based systems.

<lang 8080asm>putch: equ 2 ; CP/M 'putchar' syscall bdos: equ 5 ; CP/M BDOS entry point FF: equ 12 ; ASCII form feed org 100h mvi c,putch ; Print character (syscall goes in C register) mvi e,FF ; Form feed (argument goes in E register) jmp bdos ; Call CP/M BDOS and quit</lang>

AArch64 Assembly

Works with: as version Raspberry Pi 3B version Buster 64 bits

<lang AArch64 Assembly> /* ARM assembly AARCH64 Raspberry PI 3B */ /* program clearScreen.s */

/*******************************************/ /* Constantes file */ /*******************************************/ /* for this file see task include a file in language AArch64 assembly*/ .include "../includeConstantesARM64.inc"

.equ BUFFERSIZE, 100 /*******************************************/ /* Initialized data */ /*******************************************/ .data szMessStartPgm: .asciz "Program start \n" szMessEndPgm: .asciz "Program normal end.\n" szClear: .asciz "\33[2J" // console clear (id language C) szClear1: .byte 0x1B

                          .byte 'c'           // other console clear
                          .byte 0

szCarriageReturn: .asciz "\n" /*******************************************/ /* UnInitialized data */ /*******************************************/ .bss /*******************************************/ /* code section */ /*******************************************/ .text .global main main:

   ldr x0,qAdrszMessStartPgm                   // display start message
   bl affichageMess
   //ldr x0,qAdrszClear                        // clear screen
   ldr x0,qAdrszClear1                         // change for other clear screen
   bl affichageMess
   ldr x0,qAdrszMessEndPgm                     // display end message
   bl affichageMess

100: // standard end of the program

   mov x0,0                                    // return code
   mov x8,EXIT                                 // request to exit program
   svc 0                                       // perform system call

qAdrszMessStartPgm: .quad szMessStartPgm qAdrszMessEndPgm: .quad szMessEndPgm qAdrszClear: .quad szClear qAdrszClear1: .quad szClear1 qAdrszCarriageReturn: .quad szCarriageReturn /********************************************************/ /* File Include fonctions */ /********************************************************/ /* for this file see task include a file in language AArch64 assembly */ .include "../includeARM64.inc" </lang>

Action!

<lang Action!>proc Main()

 Put(125)

return</lang>

Ada

For systems with ANSI terminal handling:

<lang Ada>with Ada.Text_IO; procedure CLS is begin

  Ada.Text_IO.Put(ASCII.ESC & "[2J");

end CLS;</lang>

ARM Assembly

Works with: as version Raspberry Pi

/* ARM assembly Raspberry PI */ /* program clearScreen.s */

/* Constantes */ .equ STDOUT, 1 @ Linux output console .equ EXIT, 1 @ Linux syscall .equ WRITE, 4 @ Linux syscall

.equ BUFFERSIZE, 100

/* Initialized data */ .data szMessStartPgm: .asciz "Program start \n" szMessEndPgm: .asciz "Program normal end.\n" szClear: .asciz "\33[2J" @ console clear (id language C) szClear1: .byte 0x1B

                          .byte 'c'           @ other console clear
                          .byte 0

szCarriageReturn: .asciz "\n"

/* UnInitialized data */ .bss

/* code section */ .text .global main main:

   ldr r0,iAdrszMessStartPgm                   @ display start message
   bl affichageMess
   //ldr r0,iAdrszClear                        @ clear screen
   ldr r0,iAdrszClear1                         @ change for other clear screen
   bl affichageMess
   ldr r0,iAdrszMessEndPgm                     @ display end message
   bl affichageMess

100: @ standard end of the program

   mov r0, #0                                  @ return code
   mov r7, #EXIT                               @ request to exit program
   svc 0                                       @ perform system call

iAdrszMessStartPgm: .int szMessStartPgm iAdrszMessEndPgm: .int szMessEndPgm iAdrszClear: .int szClear iAdrszClear1: .int szClear1 iAdrszCarriageReturn: .int szCarriageReturn

/******************************************************************/ /* display text with size calculation */ /******************************************************************/ /* r0 contains the address of the message */ affichageMess:

   push {r0,r1,r2,r7,lr}                       @ save  registers 
   mov r2,#0                                   @ counter length */

1: @ loop length calculation

   ldrb r1,[r0,r2]                             @ read octet start position + index 
   cmp r1,#0                                   @ if 0 its over
   addne r2,r2,#1                              @ else add 1 in the length
   bne 1b                                      @ and loop 
                                               @ so here r2 contains the length of the message 
   mov r1,r0                                   @ address message in r1 
   mov r0,#STDOUT                              @ code to write to the standard output Linux
   mov r7, #WRITE                              @ code call system "write" 
   svc #0                                      @ call system
   pop {r0,r1,r2,r7,lr}                        @ restaur registers
   bx lr                                       @ return

</lang>

Arturo

<lang rebol>clear</lang>

AutoHotkey

Reference: http://www.autohotkey.com/forum/topic76532.html <lang AHK>RunWait %comspec% /c cls</lang>

AWK

<lang awk>system("clear")</lang>

Axe

<lang axe>ClrHome</lang>

BaCon

<lang freebasic>CLEAR</lang>

BASIC

Works with: QBasic

Works with: Locomotive Basic

Works with: ZX Spectrum Basic

Works with: BBC BASIC

Applesoft BASIC

Aquarius BASIC

<lang Aquarius Basic>PRINT CHR$(11);</lang>

Atari BASIC

<lang Atari Basic>PRINT CHR$(125);</lang>

BASIC256

<lang BASIC256> cls

Borra la ventana de texto</lang>

y <lang BASIC256> clg

Borra la ventana de gráficos</lang>

BBC BASIC

<lang bbcbasic> CLS</lang> or <lang bbcbasic> VDU 12</lang> or <lang bbcbasic> PRINT CHR$(12);</lang>

Commodore BASIC

<lang Commodore Basic>PRINT CHR$(147);</lang>

Works with: Commodore BASIC version 3.5,7.0

(Also works on a VIC-20 with the SuperExpander cartridge)

<lang basic>SCNCLR</lang>

GW-BASIC

IS-BASIC

<lang IS-BASIC>100 CLEAR SCREEN</lang>

PureBasic

Clears the whole console content using the current background color. <lang PureBasic>ClearConsole()</lang>

True BASIC

<lang truebasic>CLEAR END</lang>

Batch File

beeswax

Using the ANSI escape sequence Esc[2J.

Befunge

Assuming a terminal with support for ANSI escape sequences. <lang befunge>"J2["39*,,,,@</lang>

Blast

<lang blast>clear</lang>

Bracmat

C

The C version of the Minesweeper game uses curses.

If perhaps clear screen isn't used, call the function cls to do the trick.

<lang C>void cls(void) {

   printf("\33[2J");

}</lang>

Here is the cheaty way no one likes, only works on Windows.

<lang C>#include <stdio.h>

include <stdlib.h>

void main() {

   printf ("clearing screen");
   getchar();
   system("cls");

}</lang>

For Unix-likes, changing the above system("cls"); to system("clear"); usually works, however the getchar(); perhaps doesn't always work as expected if you press anything other than return. This is because of the raw vs. cooked terminal mode thing.

C#

<lang csharp>System.Console.Clear();</lang> Works on all .NET Core platforms. Throws an exception if output has been redirected to a file.

COBOL

<lang cobol> PROGRAM-ID. blank-terminal.

      DATA DIVISION.
      SCREEN SECTION.
      01  blank-screen BLANK SCREEN.
      
      PROCEDURE DIVISION.
          DISPLAY blank-screen

          GOBACK
          .</lang>

Comal

Common Lisp

<lang lisp> (format t "~C[2J" #\Esc) </lang> or it could be done passing the 'clear' command to the shell <lang lisp> (defun sh (cmd)

  "A multi-implementation function equivalent for the C function system"
  #+clisp (shell cmd)
  #+ecl (si:system cmd)
  #+sbcl (sb-ext:run-program "/bin/sh" (list "-c" cmd) :input nil :output *standard-output*)
  #+clozure (ccl:run-program "/bin/sh" (list "-c" cmd) :input nil :output *standard-output*))

(sh "clear") </lang>

ncurses

When the ncurses terminal library is used, characters are displayed on an alternate screen. Clearing that alternate screen does not clear the main screen of the terminal from which ncurses was started. To interface ncurses from Lisp, the croatoan library is used. <lang lisp>(defun clear-test ()

 ;; starting ncurses enters the alternate screen buffer of the terminal
 (with-screen (scr :input-echoing nil :input-blocking t)
   (princ "Text to be cleared" scr)
   (refresh scr)
   ;; wait for a keypress
   (get-char scr)
   (clear scr)
   (refresh scr)
   (get-char scr)))

leaving ncurses returns the terminal to the main screen buffer</lang>

D

<lang d>extern (C) nothrow {

   void disp_open();
   void disp_move(int, int);
   void disp_eeop();
   void disp_close();

}

void main() {

   disp_open();
   disp_move(0, 0);
   disp_eeop();
   disp_close();

}</lang>

Dc

Using external "clear" binary

Dc's command to execute shell commands can only be the last command of a line. That's no problem with multi line Dc programs but not very helpful in Dc oneliners: <lang dc>!clear</lang> Luckily there is a loophole: <lang dc>[ !clear ] x</lang>

Using a terminal control sequence

A common way to clear the screen with a terminal (assuming XTerm here) control sequence could be to home the cursor ("ESC[H", "1B 5B 48") and then clear to the end of the screen ("ESC[J", "1B 5B 4A"). <lang dc>16i 1B5B481B5B4A P</lang>

Delphi

Library: System.SysUtils

Library: Winapi.Windows

Stand alone function

Copy of David Heffrnan on stackoverflow [1]. <lang Delphi> uses

 System.SysUtils,
 Winapi.Windows;

procedure ClearScreen; var

 stdout: THandle;
 csbi: TConsoleScreenBufferInfo;
 ConsoleSize: DWORD;
 NumWritten: DWORD;
 Origin: TCoord;

begin

 stdout := GetStdHandle(STD_OUTPUT_HANDLE);
 Win32Check(stdout<>INVALID_HANDLE_VALUE);
 Win32Check(GetConsoleScreenBufferInfo(stdout, csbi));
 ConsoleSize := csbi.dwSize.X * csbi.dwSize.Y;
 Origin.X := 0;
 Origin.Y := 0;
 Win32Check(FillConsoleOutputCharacter(stdout, ' ', ConsoleSize, Origin, 
   NumWritten));
 Win32Check(FillConsoleOutputAttribute(stdout, csbi.wAttributes, ConsoleSize, Origin, 
   NumWritten));
 Win32Check(SetConsoleCursorPosition(stdout, Origin));

end;</lang>

Library System.Console from Jens Borrisholt

Library: System.Console

The System.Console can be found here[2] <lang Delphi>console.Clear;</lang>

Elena

ELENA 3.4 : <lang elena>public program() {

  console.clear()

}</lang>

Erlang

<lang Erlang> clear()->io:format(os:cmd("clear")). </lang>

Euphoria

<lang Euphoria>clear_screen()</lang>

F#

<lang fsharp>open System

Console.Clear()</lang>

Forth

Fortran

Fortran 2008: <lang fortran>program clear

   character(len=:), allocatable :: clear_command
   clear_command = "clear" !"cls" on Windows, "clear" on Linux and alike
   call execute_command_line(clear_command)

end program</lang>

Intel Fortran on Windows

Using console functions, one can also clear the screen without using a system command. See also Clearing the Screen on MSDN.

<lang fortran>program clear

   use kernel32
   implicit none
   integer(HANDLE) :: hStdout
   hStdout = GetStdHandle(STD_OUTPUT_HANDLE)
   call clear_console(hStdout)

contains

   subroutine clear_console(hConsole)
       integer(HANDLE) :: hConsole
       type(T_COORD) :: coordScreen = T_COORD(0, 0)
       integer(DWORD) :: cCharsWritten
       type(T_CONSOLE_SCREEN_BUFFER_INFO) :: csbi
       integer(DWORD) :: dwConSize
       
       if (GetConsoleScreenBufferInfo(hConsole, csbi) == 0) return
       dwConSize = csbi%dwSize%X * csbi%dwSize%Y
       
       if (FillConsoleOutputCharacter(hConsole, SCHAR_" ", dwConSize, &
           coordScreen, loc(cCharsWritten)) == 0) return

       if (GetConsoleScreenBufferInfo(hConsole, csbi) == 0) return
       
       if (FillConsoleOutputAttribute(hConsole, csbi%wAttributes, &
           dwConSize, coordScreen, loc(cCharsWritten)) == 0) return
           
       if (SetConsoleCursorPosition(hConsole, coordScreen) == 0) return
   end subroutine

end program</lang>

GNU Fortran on Windows

The preceding program can be compiled with GNU Fortran, with the following interface module for Windows API.

<lang fortran>module kernel32

   use iso_c_binding
   implicit none
   integer, parameter :: HANDLE = C_INTPTR_T
   integer, parameter :: PVOID = C_INTPTR_T
   integer, parameter :: LPDWORD = C_INTPTR_T
   integer, parameter :: BOOL = C_INT
   integer, parameter :: SHORT = C_INT16_T
   integer, parameter :: WORD = C_INT16_T
   integer, parameter :: DWORD = C_INT32_T
   integer, parameter :: SCHAR = C_CHAR
   integer(DWORD), parameter :: STD_INPUT_HANDLE = -10
   integer(DWORD), parameter :: STD_OUTPUT_HANDLE = -11
   integer(DWORD), parameter :: STD_ERROR_HANDLE = -12

   type, bind(C) :: T_COORD
       integer(SHORT) :: X, Y
   end type
   
   type, bind(C) :: T_SMALL_RECT
       integer(SHORT) :: Left
       integer(SHORT) :: Top
       integer(SHORT) :: Right
       integer(SHORT) :: Bottom
   end type

   type, bind(C) :: T_CONSOLE_SCREEN_BUFFER_INFO
       type(T_COORD) :: dwSize
       type(T_COORD) :: dwCursorPosition
       integer(WORD) :: wAttributes
       type(T_SMALL_RECT) :: srWindow
       type(T_COORD) :: dwMaximumWindowSize
   end type

   interface
       function FillConsoleOutputCharacter(hConsoleOutput, cCharacter, &
               nLength, dwWriteCoord, lpNumberOfCharsWritten) &
               bind(C, name="FillConsoleOutputCharacterA")
           import BOOL, C_CHAR, SCHAR, HANDLE, DWORD, T_COORD, LPDWORD
           !GCC$ ATTRIBUTES STDCALL :: FillConsoleOutputCharacter
           integer(BOOL) :: FillConsoleOutputCharacter
           integer(HANDLE), value :: hConsoleOutput
           character(kind=SCHAR), value :: cCharacter
           integer(DWORD), value :: nLength
           type(T_COORD), value :: dwWriteCoord
           integer(LPDWORD), value :: lpNumberOfCharsWritten
       end function
   end interface

   interface
       function FillConsoleOutputAttribute(hConsoleOutput, wAttribute, &
               nLength, dwWriteCoord, lpNumberOfAttrsWritten) &
               bind(C, name="FillConsoleOutputAttribute")
           import BOOL, HANDLE, WORD, DWORD, T_COORD, LPDWORD
           !GCC$ ATTRIBUTES STDCALL :: FillConsoleOutputAttribute
           integer(BOOL) :: FillConsoleOutputAttribute
           integer(HANDLE), value :: hConsoleOutput
           integer(WORD), value :: wAttribute
           integer(DWORD), value :: nLength
           type(T_COORD), value :: dwWriteCoord
           integer(LPDWORD), value :: lpNumberOfAttrsWritten
       end function
   end interface
   
   interface
       function GetConsoleScreenBufferInfo(hConsoleOutput, &
               lpConsoleScreenBufferInfo) &
               bind(C, name="GetConsoleScreenBufferInfo")
           import BOOL, HANDLE, T_CONSOLE_SCREEN_BUFFER_INFO
           !GCC$ ATTRIBUTES STDCALL :: GetConsoleScreenBufferInfo
           integer(BOOL) :: GetConsoleScreenBufferInfo
           integer(HANDLE), value :: hConsoleOutput
           type(T_CONSOLE_SCREEN_BUFFER_INFO) :: lpConsoleScreenBufferInfo
       end function
   end interface
   
   interface
       function SetConsoleCursorPosition(hConsoleOutput, dwCursorPosition) &
               bind(C, name="SetConsoleCursorPosition")
           import BOOL, HANDLE, T_COORD
           !GCC$ ATTRIBUTES STDCALL :: SetConsoleCursorPosition
           integer(BOOL) :: SetConsoleCursorPosition
           integer(HANDLE), value :: hConsoleOutput
           type(T_COORD), value :: dwCursorPosition
       end function
   end interface
   
   interface
       function GetStdHandle(nStdHandle) bind(C, name="GetStdHandle")
           import HANDLE, DWORD
           !GCC$ ATTRIBUTES STDCALL :: GetStdHandle
           integer(HANDLE) :: GetStdHandle
           integer(DWORD), value :: nStdHandle
       end function
   end interface

end module </lang>

FreeBASIC

<lang freebasic>' FB 1.05.0 Win64

' FreeBASIC has a built in Cls command which clears the console on Windows ' but it may still be possible to scroll the console to view its ' previous contents. The following command prevents this.

Shell("Cls") Sleep</lang>

Furor

<lang go> cls </lang> Yet another solution: <lang go> ."\z" </lang>

Go

External command

Probably most reliable way to clear the screen. <lang go>package main

import (

   "os"
   "os/exec"

)

func main() {

   c := exec.Command("clear")
   c.Stdout = os.Stdout
   c.Run()

}</lang>

ANSI escape code

Simplest, if your terminal supports the ANSI code you want. <lang go>package main

import "fmt"

func main() {

   fmt.Print("\033[2J")

}</lang>

Ncurses

More complex, but works across multiple terminal types.

Library: curses

<lang go>package main

import (

   "log"
   "time"

   "code.google.com/p/goncurses"

)

func main() {

   s, err := goncurses.Init()
   if err != nil {
       log.Fatal("goncurses:", err)
   }
   defer goncurses.End()
   s.Println("Clearing screen...")
   s.Refresh()
   time.Sleep(1 * time.Second)

   s.Clear() // clear screen

   // Goncurses saves the screen on Init and restores it on End.  This
   // GetChar() allows you to see the effect of the program before it exits.
   s.GetChar() // press any key to continue

}</lang>

GUISS

This will only work if the terminal is sitting at a prompt. <lang guiss>Window:Terminal,Type:clear[enter]</lang>

Haskell

<lang Haskell> import System.Console.ANSI

main = clearScreen </lang>

Icon and Unicon

Example works for both Icon and Unicon. Determine which system command to call by querying &features at run time. Alternately, the related preprocessor symbols can be used to select the operating system. <lang Icon>procedure main ()

 if &features == "MS Windows" then system("cls")  # Windows
 else if &features == "UNIX" then system("clear") # Unix

end</lang>

J

Note: this is specific the java+gdi based J ide. <lang j>smwrite_jijs_ </lang>

Java

Using the ANSI escape sequence: <lang java>public class Clear {

   public static void main (String[] args)
   {
       System.out.print("\033[2J");
   }

}</lang> An alternative sequence: <lang java>public class Clear {

   public static void main (String[] args)
   {
       System.out.print("\033\143");
   }

}</lang>

jq

<lang jq>"\u001B[2J"</lang> Example: <lang sh>$ jq -n '"\u001B[2J"'</lang>

Jsish

Using ANSI terminal control codes. <lang javascript>/* Terminal Control, clear the screen, in Jsish */ function cls() { printf('\u001b[2J'); }

cls();

/*

!EXPECTSTART!

cls() ==> ^[[2Jundefined

!EXPECTEND!

/</lang>

Output:

prompt$ jsish -u terminalControlClear.jsi
[PASS] terminalControlClear.jsi

Julia

<lang julia> println("\33[2J") </lang>

Kotlin

Works with: Ubuntu version 14.04

<lang scala>// version 1.1.2

fun main(args: Array<String>) {

   println("\u001Bc")  // Esc + c

}</lang>

Lasso

<lang Lasso>local( esc = decode_base64('Gw==') )

stdout(#esc + '[2J')</lang>

Logo

<lang logo>cleartext</lang> There is a separate command to reset the turtle graphics window. <lang logo>clearscreen cs ; abbreviation for clearscreen clean ; like cs, but doesn't reset turtle position</lang>

Lua

Unix, Linux

<lang lua>os.execute( "clear" )</lang>

Windows

<lang lua>os.execute( "cls" )</lang>

M2000 Interpreter

We can clear the screen with Form, Cls, Window statements. Each one perform something on the console form except clear it. Form change the size of letters using the size of window. Window change all. Cls change the background color, or use the same (is optional) and optional can set the line for the split screen (from that line we have scrolling). Also we can use Linespace statement (in twips) to set the line space. Statement Form set linespace automatic to give space between lines to full use of the window.

<lang M2000 Interpreter> Module Checkit {

     Pen 14 ' yellow
     \\ using form we set characters by rows
     \\ this clear the screen
     Form 80, 40
     \\ magenta for background, all form for vertical scrolling
     Cls 5, 0
     Print "wait... half second"
     Wait 500
     \\ clear using background color
     Cls 
     \\ set the background (using html number for color), and set 4th line as top
     \\ for scrolling
     Cls #11bb22, 3
     Print "This is in 4th line"
     Wait  1000
     \\ now we center the form, using 12000 twips by 8000twips as border
     \\ form inside maybe smaller
     \\ font size is 16pt of current font
     Font "Courier New"
     Window 16, 12000, 8000;
     Print "This is first line"
     Wait 1000
     Font "Arial"
     \\ set the console form to screen 0, maximized
     Window 16, 0
     Cls 5   ' magenta
     Back {
           Cls 15 ' white border      
     }

} checkit </lang>

Mathematica/Wolfram Language

Delegating to clear on terminal enabled OS(Mac Os, Linux) <lang Mathematica>Run["clear"];</lang>

Nanoquery

Nemerle

Exactly as C#. Because of possible (probable) ambiguity, this is one time it may be prudent to use: <lang Nemerle>Console.Clear();</lang> rather than importing the Console class with using System.Console; and calling as: <lang Nemerle>Clear();</lang>

NewLISP

<lang NewLISP> (! "clear") </lang> In the newLISP command shell, this syntax is also proper: <lang NewLISP> !clear </lang>

Nim

<lang nim>import osproc discard execCmd "clear"</lang>

NS-HUBASIC

OCaml

Using the library ANSITerminal:

<lang ocaml>#load "unix.cma"

directory "+ANSITerminal"
load "ANSITerminal.cma"

open ANSITerminal

let () =

 erase Screen</lang>

Octave

<lang Octave> system clear;</lang> <lang Octave> system('clear');</lang>

Pascal

<lang Pascal>clrscr;</lang> <lang Pascal>page(output); { UCSD Pascal }</lang>

Perl

Assuming some ANSI terminal, easiest way is call your system's clear command: <lang perl>system('clear')</lang>

If it's needed often: <lang perl>$clear = `clear`; # clear simply prints some escape sequence, cache it

... later:

print $clear;</lang>

We can also obtain the sequence using the Term::Cap module:

<lang perl>use Term::Cap;

$terminal = Term::Cap->Tgetent(); $clear = $terminal->Tputs('cl'); print $clear;</lang>

<lang perl>#on Windows using Powershell or WT.exe system('cls');</lang>

Phix

<lang Phix>clear_screen()</lang>

PicoLisp

<lang PicoLisp>(call 'clear)</lang>

PowerShell

<lang powershell>Clear-Host</lang>

ProDOS

<lang ProDOS>clearscurrentscreentext</lang>

Python

Works with: Python version 2.6

Works with: Ubuntu version 10.10

To clear the screen on Windows, replace 'clear' with 'cls'

<lang python>import os os.system("clear")</lang>

Or similar to C example (won't work in Winsows console, since it does not recognize ANSI sequences):

<lang python>print "\33[2J"</lang>

On Windows, using functions from the kernel32 DLL:

<lang python>from ctypes import *

STD_OUTPUT_HANDLE = -11

class COORD(Structure):

   pass

COORD._fields_ = [("X", c_short), ("Y", c_short)]

class SMALL_RECT(Structure):

   pass

SMALL_RECT._fields_ = [("Left", c_short), ("Top", c_short), ("Right", c_short), ("Bottom", c_short)]

class CONSOLE_SCREEN_BUFFER_INFO(Structure):

   pass

CONSOLE_SCREEN_BUFFER_INFO._fields_ = [

   ("dwSize", COORD),
   ("dwCursorPosition", COORD),
   ("wAttributes", c_ushort),
   ("srWindow", SMALL_RECT),
   ("dwMaximumWindowSize", COORD)

]

def clear_console():

   h = windll.kernel32.GetStdHandle(STD_OUTPUT_HANDLE)

   csbi = CONSOLE_SCREEN_BUFFER_INFO()
   windll.kernel32.GetConsoleScreenBufferInfo(h, pointer(csbi))
   dwConSize = csbi.dwSize.X * csbi.dwSize.Y

   scr = COORD(0, 0)
   windll.kernel32.FillConsoleOutputCharacterA(h, c_char(b" "), dwConSize, scr, pointer(c_ulong()))
   windll.kernel32.FillConsoleOutputAttribute(h, csbi.wAttributes, dwConSize, scr, pointer(c_ulong()))
   windll.kernel32.SetConsoleCursorPosition(h, scr)

clear_console()</lang>

Quackery

Translation of: Python

On some platforms the screen will not be cleared until the output buffer is flushed e.g. by a cr/lf.

<lang Quackery> [ $ &print("\33[2J",end=)& python ] is clearscreen</lang>

R

<lang R>cat("\33[2J")</lang> Or with system calls <lang R># Unix system("clear")

Windows

system("cls")</lang>

Racket

lang racket

(require (planet neil/charterm:3:0)) (with-charterm

(void (charterm-clear-screen)))

</lang>

Raku

(formerly Perl 6) <lang perl6>sub clear { print qx[clear] } clear;</lang>

Retro

<lang Retro>clear</lang>

REXX

generic

The REXX programming language does not include a facility to clear the screen natively.

However, it is possile to execute an external system command to achieve this task.

Below is some generic-type boilerplate (REXX) code which (possibly) determines:

which REXX is being used
which operating system is being used
which (external) program to clear the screen

Also, not germane to this Rosetta Code task, the boilerplate code also possibly determines (among other things):

if a particular documentation is to be shown
which system pool name is to be used for system environmental variables
which version of REXX is being used
if the program is being invoked as a function, command, or subroutine

The following code works for:

PC/REXX
Personal REXX
CMS REXX
TSO REXX
R4 REXX
ROO REXX
KEXX
REXX compiler
Regina REXX

The intent of the program's boilerplate code is to be able to be executed under most REXXes under most operating systems without changing the boilerplate REXX code. <lang rexx>/*REXX boilerplate determines how to clear screen (under various REXXes)*/ trace off; parse arg ! /*turn off tracing; get C.L. args*/ if !all(arg()) then exit /*Doc request? Show, then exit.*/ if !cms then address /*Is this CMS? Use this address.*/

!cls /*clear the (terminal) screen. */ /* ◄═══ this is where "it" happens.*/

exit /*stick a fork in it, we're done.*/ /*═════════════════════════════general 1-line subs══════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════*/ !all: !!=!;!=space(!);upper !;call !fid;!nt=right(!var('OS'),2)=='NT';!cls=word('CLS VMFCLEAR CLRSCREEN',1+!cms+!tso*2);if arg(1)\==1 then return 0;if wordpos(!,'? ?SAMPLES ?AUTHOR ?FLOW')==0 then return 0;!call=']$H';call '$H' !fn !;!call=;return 1 !cal: if symbol('!CALL')\=="VAR" then !call=; return !call !env: !env='ENVIRONMENT'; if !sys=='MSDOS'|!brexx|!r4|!roo then !env='SYSTEM'; if !os2 then !env='OS2'!env; !ebcdic=1=='f0'x; if !crx then !env='DOS'; return !fid: parse upper source !sys !fun !fid . 1 . . !fn !ft !fm .; call !sys; if !dos then do; _=lastpos('\',!fn); !fm=left(!fn,_); !fn=substr(!fn,_+1); parse var !fn !fn '.' !ft; end; return word(0 !fn !ft !fm,1+('0'arg(1))) !rex: parse upper version !ver !vernum !verdate .; !brexx='BY'==!vernum; !kexx='KEXX'==!ver; !pcrexx='REXX/PERSONAL'==!ver|'REXX/PC'==!ver; !r4='REXX-R4'==!ver; !regina='REXX-REGINA'==left(!ver,11); !roo='REXX-ROO'==!ver; call !env; return !sys: !cms=!sys=='CMS'; !os2=!sys=='OS2'; !tso=!sys=='TSO'|!sys=='MVS'; !vse=!sys=='VSE'; !dos=pos('DOS',!sys)\==0|pos('WIN',!sys)\==0|!sys=='CMD'; !crx=left(!sys,6)=='DOSCRX'; call !rex; return !var: call !fid; if !kexx then return space(dosenv(arg(1))); return space(value(arg(1),,!env))</lang>

Regina

The regina interpreter supports the rexxcurses plugin, which provides a facility to clear the screen (not shown here).

Ring

<lang Ring>system('clear')</lang>

Ruby

<lang Ruby>system 'clear'</lang>

Or, without reliance on the command line: (equivalent to `clear`) <lang Ruby>puts "\e[H\e[2J"</lang>

Rust

<lang rust>print!("\x1B[2J");</lang>

Or using casting:

<lang rust>print!("{}[2J", 27 as char);</lang>

Scala

Library: Scala

<lang Scala>object Cls extends App {print("\033[2J")}</lang>

Seed7

The function clear is portable and clears the console window. Clear is based on terminfo respectively the Windows console API. A portable function to clear cannot rely on shell respectively cmd.exe commands, because Windows uses CLS and Unix shells use CLEAR, to clear a screen. ANSI terminal escape sequences are also not 100% portable, since not all terminals accept them.

<lang seed7>$ include "seed7_05.s7i";

 include "console.s7i";

const proc: main is func

 local
   var text: console is STD_NULL;
 begin
   console := open(CONSOLE);
   clear(console);
   # Terminal windows often restore the previous
   # content, when a program is terminated. Therefore
   # the program waits until Return/Enter is pressed.
   readln;
 end func;</lang>

Sidef

Using a cached-function: <lang ruby>func clear { print(static x = `clear`) }; clear();</lang>

Directly invoking the `clear` command: <lang ruby>Sys.run('clear');</lang>

Alternatively, without reliance on the command line: <lang ruby>print "\e[3J\e[H\e[2J";</lang>

Smalltalk

<lang smalltalk>Transcript clear.</lang>

SmileBASIC

SmileBASIC's text screen is mixed in with its graphics screen, background screen, and sprites screen.

Text screen only

To clear just the text screen: <lang smilebasic>CLS</lang>

All screens

Clearing all of the screens, and resetting display options can be done with: <lang smilebasic>ACLS</lang>

SPL

<lang spl>#.clear()</lang>

Standard ML

Works with: Unix

<lang sml>fun clearScreen () =

 let
   val strm = TextIO.openOut (Posix.ProcEnv.ctermid ())
 in
   TextIO.output (strm, "\^[[H\^[[2J");
   TextIO.closeOut strm
 end</lang>

Stata

The cls command clears the Results window, which is the closest to a terminal in Stata.

Tcl

This only works on systems with ANSI terminal handling, i.e., Unix platforms. <lang tcl>puts -nonewline "\033\[2J" flush stdout</lang>

UNIX Shell

The clear command can be used to clear the terminal screen:

Works with: Bourne Shell

<lang bash>clear

Alternative method using tput

tput clear</lang>