How can I clear console

Question

As in the title. How can I clear console in C++?

Solution 1

For pure C++

You can't. C++ doesn't even have the concept of a console.

The program could be printing to a printer, outputting straight to a file, or being redirected to the input of another program for all it cares. Even if you could clear the console in C++, it would make those cases significantly messier.

See this entry in the comp.lang.c++ FAQ:

• http://www.parashift.com/c++-faq-lite/input-output.html#faq-15.20

OS-Specific

If it still makes sense to clear the console in your program, and you are interested in operating system specific solutions, those do exist.

For Windows (as in your tag), check out this link:

• How do we clear the console in assembly?

Edit: This answer previously mentioned using system("cls");, because Microsoft said to do that. However it has been pointed out in the comments that this is not a safe thing to do. I have removed the link to the Microsoft article because of this problem.

Libraries (somewhat portable)

ncurses is a library that supports console manipulation:

• http://www.gnu.org/software/ncurses/ (runs on Posix systems)
• http://gnuwin32.sourceforge.net/packages/ncurses.htm (somewhat old Windows port)

Solution 2

For Windows, via Console API:

void clear() {
    COORD topLeft  = { 0, 0 };
    HANDLE console = GetStdHandle(STD_OUTPUT_HANDLE);
    CONSOLE_SCREEN_BUFFER_INFO screen;
    DWORD written;

    GetConsoleScreenBufferInfo(console, &screen);
    FillConsoleOutputCharacterA(
        console, ' ', screen.dwSize.X * screen.dwSize.Y, topLeft, &written
    );
    FillConsoleOutputAttribute(
        console, FOREGROUND_GREEN | FOREGROUND_RED | FOREGROUND_BLUE,
        screen.dwSize.X * screen.dwSize.Y, topLeft, &written
    );
    SetConsoleCursorPosition(console, topLeft);
}

It happily ignores all possible errors, but hey, it's console clearing. Not like system("cls") handles errors any better.

For *nixes, you usually can go with ANSI escape codes, so it'd be:

void clear() {
    // CSI[2J clears screen, CSI[H moves the cursor to top-left corner
    std::cout << "\x1B[2J\x1B[H";
}

Using system for this is just ugly.

Solution 3

For Linux/Unix and maybe some others but not for Windows before 10 TH2:

printf("\033c");

will reset terminal.

Solution 4

The easiest way for me without having to reinvent the wheel.

void Clear()
{
#if defined _WIN32
    system("cls");
    //clrscr(); // including header file : conio.h
#elif defined (__LINUX__) || defined(__gnu_linux__) || defined(__linux__)
    system("clear");
    //std::cout<< u8"\033[2J\033[1;1H"; //Using ANSI Escape Sequences 
#elif defined (__APPLE__)
    system("clear");
#endif
}

• On Windows you can use "conio.h" header and call clrscr function to avoid the use of system funtion.

#include <conio.h>
clrscr();

• On Linux you can use ANSI Escape sequences to avoid use of system function. Check this reference ANSI Escape Sequences

    std::cout<< u8"\033[2J\033[1;1H"; 

• On MacOS Investigating...

Solution 5

outputting multiple lines to window console is useless..it just adds empty lines to it. sadly, way is windows specific and involves either conio.h (and clrscr() may not exist, that's not a standard header either) or Win API method

#include <windows.h>

void ClearScreen()
  {
  HANDLE                     hStdOut;
  CONSOLE_SCREEN_BUFFER_INFO csbi;
  DWORD                      count;
  DWORD                      cellCount;
  COORD                      homeCoords = { 0, 0 };

  hStdOut = GetStdHandle( STD_OUTPUT_HANDLE );
  if (hStdOut == INVALID_HANDLE_VALUE) return;

  /* Get the number of cells in the current buffer */
  if (!GetConsoleScreenBufferInfo( hStdOut, &csbi )) return;
  cellCount = csbi.dwSize.X *csbi.dwSize.Y;

  /* Fill the entire buffer with spaces */
  if (!FillConsoleOutputCharacter(
    hStdOut,
    (TCHAR) ' ',
    cellCount,
    homeCoords,
    &count
    )) return;

  /* Fill the entire buffer with the current colors and attributes */
  if (!FillConsoleOutputAttribute(
    hStdOut,
    csbi.wAttributes,
    cellCount,
    homeCoords,
    &count
    )) return;

  /* Move the cursor home */
  SetConsoleCursorPosition( hStdOut, homeCoords );
  }

For POSIX system it's way simpler, you may use ncurses or terminal functions

#include <unistd.h>
#include <term.h>

void ClearScreen()
  {
  if (!cur_term)
    {
    int result;
    setupterm( NULL, STDOUT_FILENO, &result );
    if (result <= 0) return;
    }

  putp( tigetstr( "clear" ) );
  }

View more solutions

Comments

[Jerry Coffin]

On what OS? It's quite a bit different on Linux vs. Windows, just for one example. If you want it for Windows, see: stackoverflow.com/questions/5866529/…

[Thomas B]

I want to reset console view sometimes. I dont want to spam console with million of newlines.

[Merlyn Morgan-Graham]

"Using system for this is just ugly." - Why? Sure looks cleaner to me :)

[Cat Plus Plus]

@MerlynMorgan-Graham: It spawns a shell process to clear a friggin' console. In what way is that a clean solution? :P It's like using echo via system() instead of writing to stdout.

[Merlyn Morgan-Graham]

One liner FTW! ;) Yes, I'm being facetious. The fact that it spawns a shell process is good info for your answer, tho. +1 for the *nix version.

[JdeBP]

Using system() is a common mistake. So, too, is your suggested method for Unices. This is what one should do on POSIX systems. You got the Win32 part right, albeit that you didn't incorporate the "scroll back" convention.

[LoveToCode]

[Error] 'System ' has not been declared.

[CMS_95]

system("cls") is not a portable solution to this issue, however it does work on Windows systems.

[Lightness Races in Orbit]

That is not a "module". C++ does not have "modules". Furthermore, stdlib.h is specified by the C standard, and has nothing to do with "importing windows commands" nor indeed Windows itself. Other than that nitpicking, you're fine.

[FryGuy]

This is for c++/CLI (aka .NET c++)

[Dialecticus]

Already mentioned in the accepted answer. No new information here.

[cojack]

"It used to be a function in <conio.h>, in old Borland C compilers. It's not a C++ standard function." stackoverflow.com/a/930141/1058115

[user2445507]

@JdeBP your link is dead. Here's an archive link

[JdeBP]

No need for archives. jdebp.eu./FGA/clearing-the-tui-screen.html#CLS exists.

[Nathan Smiechowski]

Then get rid of cout/wcout and simply pipe stuff to system("echo " + your output);

[Agi Hammerthief]

This isn't what the OP is looking for. Read the comment added to the question.

[John Doe]

Note that any call to system() could be a security issue.

[HolyBlackCat]

This was already suggested in several other answers.