Löschen des Bildschirms

Es gibt drei Möglichkeiten, den Bildschirm in einer Konsolenanwendung zu löschen.

Beispiel 1

Die erste Methode besteht darin, die Anwendung für virtuelle Terminalausgabesequenzen einzurichten und dann den Befehl "Clear screen" aufzurufen.

#include <windows.h>

int main(void)
{
    HANDLE hStdOut;

    hStdOut = GetStdHandle(STD_OUTPUT_HANDLE);

    // Fetch existing console mode so we correctly add a flag and not turn off others
    DWORD mode = 0;
    if (!GetConsoleMode(hStdOut, &mode))
    {
        return ::GetLastError();
    }

    // Hold original mode to restore on exit to be cooperative with other command-line apps.
    const DWORD originalMode = mode;
    mode |= ENABLE_VIRTUAL_TERMINAL_PROCESSING;

    // Try to set the mode.
    if (!SetConsoleMode(hStdOut, mode))
    {
        return ::GetLastError();
    }

    // Write the sequence for clearing the display.
    DWORD written = 0;
    PCWSTR sequence = L"\x1b[2J";
    if (!WriteConsoleW(hStdOut, sequence, (DWORD)wcslen(sequence), &written, NULL))
    {
        // If we fail, try to restore the mode on the way out.
        SetConsoleMode(hStdOut, originalMode);
        return ::GetLastError();
    }

    // To also clear the scroll back, emit L"\x1b[3J" as well.
    // 2J only clears the visible window and 3J only clears the scroll back.

    // Restore the mode on the way out to be nice to other command-line applications.
    SetConsoleMode(hStdOut, originalMode);

    return 0;
}

Weitere Variationen zu diesem Befehl finden Sie in der Dokumentation zu virtuellen Terminalsequenzen auf Erase In Display.

Beispiel 2

Die zweite Methode besteht darin, eine Funktion zu schreiben, um den Inhalt des Bildschirms oder Puffers zu scrollen und eine Füllung für den angezeigten Raum festzulegen.

Dies entspricht dem Verhalten der Eingabeaufforderung promptcmd.exe.

#include <windows.h>

void cls(HANDLE hConsole)
{
    CONSOLE_SCREEN_BUFFER_INFO csbi;
    SMALL_RECT scrollRect;
    COORD scrollTarget;
    CHAR_INFO fill;

    // Get the number of character cells in the current buffer.
    if (!GetConsoleScreenBufferInfo(hConsole, &csbi))
    {
        return;
    }

    // Scroll the rectangle of the entire buffer.
    scrollRect.Left = 0;
    scrollRect.Top = 0;
    scrollRect.Right = csbi.dwSize.X;
    scrollRect.Bottom = csbi.dwSize.Y;

    // Scroll it upwards off the top of the buffer with a magnitude of the entire height.
    scrollTarget.X = 0;
    scrollTarget.Y = (SHORT)(0 - csbi.dwSize.Y);

    // Fill with empty spaces with the buffer's default text attribute.
    fill.Char.UnicodeChar = TEXT(' ');
    fill.Attributes = csbi.wAttributes;

    // Do the scroll
    ScrollConsoleScreenBuffer(hConsole, &scrollRect, NULL, scrollTarget, &fill);

    // Move the cursor to the top left corner too.
    csbi.dwCursorPosition.X = 0;
    csbi.dwCursorPosition.Y = 0;

    SetConsoleCursorPosition(hConsole, csbi.dwCursorPosition);
}

int main(void)
{
    HANDLE hStdout;

    hStdout = GetStdHandle(STD_OUTPUT_HANDLE);

    cls(hStdout);

    return 0;
}

Beispiel 3

Die dritte Methode besteht darin, eine Funktion zu schreiben, um den Bildschirm mithilfe der Funktionen FillConsoleOutputCharacter und FillConsoleOutputAttribute programmgesteuert zu löschen.

Diese Verfahren werden im folgenden Codebeispiel veranschaulicht:

#include <windows.h>

void cls(HANDLE hConsole)
{
    COORD coordScreen = { 0, 0 };    // home for the cursor
    DWORD cCharsWritten;
    CONSOLE_SCREEN_BUFFER_INFO csbi;
    DWORD dwConSize;

    // Get the number of character cells in the current buffer.
    if (!GetConsoleScreenBufferInfo(hConsole, &csbi))
    {
        return;
    }

    dwConSize = csbi.dwSize.X * csbi.dwSize.Y;

    // Fill the entire screen with blanks.
    if (!FillConsoleOutputCharacter(hConsole,        // Handle to console screen buffer
                                    (TCHAR)' ',      // Character to write to the buffer
                                    dwConSize,       // Number of cells to write
                                    coordScreen,     // Coordinates of first cell
                                    &cCharsWritten)) // Receive number of characters written
    {
        return;
    }

    // Get the current text attribute.
    if (!GetConsoleScreenBufferInfo(hConsole, &csbi))
    {
        return;
    }

    // Set the buffer's attributes accordingly.
    if (!FillConsoleOutputAttribute(hConsole,         // Handle to console screen buffer
                                    csbi.wAttributes, // Character attributes to use
                                    dwConSize,        // Number of cells to set attribute
                                    coordScreen,      // Coordinates of first cell
                                    &cCharsWritten))  // Receive number of characters written
    {
        return;
    }

    // Put the cursor at its home coordinates.
    SetConsoleCursorPosition(hConsole, coordScreen);
}

int main(void)
{
    HANDLE hStdout;

    hStdout = GetStdHandle(STD_OUTPUT_HANDLE);

    cls(hStdout);

    return 0;
}