Home » C++ » How can I clear console

How can I clear console

Posted by: admin November 29, 2017 Leave a comment

Questions:

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

Answers:

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:

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 these links:

The simplest of these solutions is:

#include <stdlib.h>

int main(int argc, char* argv[])
{
  system("cls");
  return 0;
}

Libraries (somewhat portable)

ncurses is a library that supports console manipulation:

Questions:
Answers:

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.

Questions:
Answers:

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

printf("3c");

will reset terminal.

Questions:
Answers:
// #define _WIN32_WINNT 0x0500     // windows >= 2000 
#include <windows.h> 
#include <iostream>

using namespace std; 

void pos(short C, short R)
{
    COORD xy ;
    xy.X = C ;
    xy.Y = R ;
    SetConsoleCursorPosition( 
    GetStdHandle(STD_OUTPUT_HANDLE), xy);
}
void cls( )
{
    pos(0,0);
    for(int j=0;j<100;j++)
    cout << string(100, ' ');
    pos(0,0);
} 

int main( void )
{
    // write somthing and wait 
    for(int j=0;j<100;j++)
    cout << string(10, 'a');
    cout << "\n\npress any key to cls... ";
    cin.get();

    // clean the screen
    cls();

    return 0;
}

Questions:
Answers:

Use system("cls") to clear the screen:

#include <stdlib.h>

int main(void)
{
    system("cls");
    return 0;
}

Questions:
Answers:

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" ) );
  }

Questions:
Answers:

To clear the screen you will first need to include a module:

#include <stdlib.h>

this will import windows commands. Then you can use the ‘system’ function to run Batch commands (which edit the console). On Windows in C++, the command to clear the screen would be:

system("CLS");

And that would clear the console. The entire code would look like this:

#include <iostream>
#include <stdlib.h>

using namespace std;

int main()
{
system("CLS");
}

And that’s all you need! Goodluck 🙂

Questions:
Answers:

In Windows:

#include <cstdlib>

int main() { 
    std::system("cls");
    return 0;
}

In Linux/Unix:

#include <cstdlib>

int main() { 
    std::system("clear");
    return 0;
}

Questions:
Answers:

This is REALLY choppy but try:

void cls() {
    for (int i = 0; i < 250; ++i) {
        std::cout << endl;
    }
}

Questions:
Answers:

This is hard for to do on MAC seeing as it doesn’t have access to the windows functions that can help clear the screen. My best fix is to loop and add lines until the terminal is clear and then run the program. However this isn’t as efficient or memory friendly if you use this primarily and often.

void clearScreen(){
    int clear = 5;
    do {
        cout << endl;
        clear -= 1;
    } while (clear !=0);
}

Questions:
Answers:

Use System::Console::Clear();

This will clear (empty) the buffer

Questions:
Answers:

You can use the operating system’s clear console method via system(“”);

for windows it would be system(“cls”); for example

and instead of releasing three different codes for different operating systems. just make a method to get what os is running.

you can do this by detecting if unique system variables exist with #ifdef

e.g.

enum OPERATINGSYSTEM = {windows = 0, mac = 1, linux = 2 /*etc you get the point*/};

void getOs(){
    #ifdef _WIN32
        return OPERATINGSYSTEM.windows
    #elif __APPLE__ //etc you get the point

    #endif
}

int main(){
    int id = getOs();
    if(id == OPERATINGSYSTEM.windows){
        system("CLS");
    }else if (id == OPERATINGSYSTEM.mac){
        system("CLEAR");
    } //etc you get the point

}

Questions:
Answers:
#include <cstdlib>

void cls(){
#if defined(_WIN32) //if windows
    system("cls");

#else
    system("clear");    //if other
#endif  //finish

}

The just call cls() anywhere

Questions:
Answers:

use: clrscr();

#include <iostream>
using namespace std;
int main()
      {           
         clrscr();
         cout << "Hello World!" << endl;
         return 0;
      }

Questions:
Answers:

edit: completely redone question

Simply test what system they are on and send a system command depending on the system. though this will be set at compile time

#ifdef __WIN32
    system("cls");
#else
    system("clear"); // most other systems use this
#endif

This is a completely new method!

Questions:
Answers:

The easiest way would be to flush the stream multiple times ( ideally larger then any possible console ) 1024*1024 is likely a size no console window could ever be.

int main(int argc, char *argv)
{
  for(int i = 0; i <1024*1024; i++)
      std::cout << ' ' << std::endl;

  return 0;
}

The only problem with this is the software cursor; that blinking thing ( or non blinking thing ) depending on platform / console will be at the end of the console, opposed to the top of it. However this should never induce any trouble hopefully.