Clear command line with C on windows

As an alternative conio.h

or system call, just an implementation (I suppose similar to the conio library) of how this is done on Windows.

#include <windows.h>

int main(void){
    HANDLE hStdout; 
    CONSOLE_SCREEN_BUFFER_INFO csbiInfo; 
    DWORD dwCells, dwWritten;

    // Get console handle
    hStdout = GetStdHandle(STD_OUTPUT_HANDLE);     

    // Retrieve console information
    if (GetConsoleScreenBufferInfo(hStdout, &csbiInfo)) {

        // Calc console cells
        dwCells = csbiInfo.dwSize.Y * csbiInfo.dwSize.X;

        // Initialize cursor position
        csbiInfo.dwCursorPosition.X = 0;
        csbiInfo.dwCursorPosition.Y = 0;

        // Replace all characters in console with spaces
        FillConsoleOutputCharacterA( hStdout, ' ', dwCells, csbiInfo.dwCursorPosition,  &dwWritten);
        // Replace all attributes in console with the default
        FillConsoleOutputAttribute( hStdout, csbiInfo.wAttributes, dwCells, csbiInfo.dwCursorPosition, &dwWritten );
        // Position the cursor
        SetConsoleCursorPosition( hStdout, csbiInfo.dwCursorPosition );
    }

    return 0;
}

      

        
        
        
      

    

edited to follow the comments

After some testing, this is (more or less) how the command is cls

implemented in cmd.exe

(at least in Windows 7 64)

#include <windows.h>

int main(void){
    HANDLE hStdout; 
    CONSOLE_SCREEN_BUFFER_INFO csbiInfo; 
    COORD destinationPoint;
    SMALL_RECT sourceArea;
    CHAR_INFO Fill;

    // Get console handle
    hStdout = GetStdHandle(STD_OUTPUT_HANDLE);     

    // Retrieve console information
    if (GetConsoleScreenBufferInfo(hStdout, &csbiInfo)) {
        // Select all the console buffer as source
        sourceArea.Top = 0;
        sourceArea.Left = 0;
        sourceArea.Bottom = csbiInfo.dwSize.Y - 1;
        sourceArea.Right = csbiInfo.dwSize.X - 1;

        // Select a place out of the console to move the buffer
        destinationPoint.X = 0;
        destinationPoint.Y = 0 - csbiInfo.dwSize.Y;

        // Configure fill character and attributes
        Fill.Char.AsciiChar = ' ';
        Fill.Attributes =  csbiInfo.wAttributes;

        // Move all the information out of the console buffer and init the buffer
        ScrollConsoleScreenBuffer( hStdout, &sourceArea, NULL, destinationPoint, &Fill);

        // Position the cursor
        destinationPoint.X = 0;
        destinationPoint.Y = 0;
        SetConsoleCursorPosition( hStdout, destinationPoint );
    }

    return 0;
}

      

        
        
        
      

    

Instead of calling api functions to fill the buffer with the required character and attribute, the full buffer is scrolled and when the scroll operation fills an empty area, the buffer is initialized. All in one api call.

edited . This is the equivalent ansi escape code. Clear your console, but save your history. This does not initialize a full console buffer, only provides a clean console window by scrolling through the visible window or buffer if needed.

#include <windows.h>

int main(void){
    HANDLE hStdout; 
    CONSOLE_SCREEN_BUFFER_INFO csbiInfo; 
    COORD destinationPoint;
    SMALL_RECT sourceArea;
    CHAR_INFO Fill;
    SHORT delta, end;

    // Get console handle
    hStdout = GetStdHandle(STD_OUTPUT_HANDLE);     

    // Retrieve console information
    if (GetConsoleScreenBufferInfo(hStdout, &csbiInfo)) {

        // How many lines needs the window to be moved to be clear
        delta = (csbiInfo.dwCursorPosition.Y) - csbiInfo.srWindow.Top;

        // Where the bottom of the window will fall after moving
        end = csbiInfo.srWindow.Bottom + delta;

        // If the window get out of the console buffer, it is necessary to scroll the buffer
        if (end >= csbiInfo.dwSize.Y){
            // Select all the console buffer as source
            sourceArea.Top = 0;
            sourceArea.Left = 0;
            sourceArea.Bottom = csbiInfo.dwSize.Y-1;
            sourceArea.Right = csbiInfo.dwSize.X-1;

            // Select the target point for the movement
            destinationPoint.X = 0;
            destinationPoint.Y = 0 - delta ;

            // Configure fill character and attributes for the empty area
            Fill.Char.AsciiChar = ' ';
            Fill.Attributes =  csbiInfo.wAttributes;

            // Scroll the buffer and init the end zone
            ScrollConsoleScreenBuffer( hStdout, &sourceArea, NULL, destinationPoint, &Fill);

            // Adjust new cursor position
            destinationPoint.X = 0;
            destinationPoint.Y = csbiInfo.dwSize.Y - (csbiInfo.srWindow.Bottom - csbiInfo.srWindow.Top + 1);

        } else {
            // No buffer scroll is needed. Adjust the new cursor position
            destinationPoint.X = 0;
            destinationPoint.Y = csbiInfo.dwCursorPosition.Y + 1;
        }

        // In any case, the visible window needs to be moved depending on the new cursor position
        sourceArea.Top = destinationPoint.Y;
        sourceArea.Left = destinationPoint.X;
        sourceArea.Bottom = destinationPoint.Y + (csbiInfo.srWindow.Bottom - csbiInfo.srWindow.Top + 1) -1 ;
        sourceArea.Right = csbiInfo.dwSize.X-1;

        // Place the visible window in the required place over the buffer
        SetConsoleWindowInfo(hStdout, TRUE, &sourceArea);

        // Place the cursor in its final position
        SetConsoleCursorPosition( hStdout, destinationPoint );
    }

    return 0;
}