clear()

static void xtd::console::clear ( )

static

Clears the console buffer and corresponding console window of display information.

Remarks

Using the clear method is equivalent invoking the MS-DOS cls command in the command prompt window.

When the Clear method is called, the cursor automatically scrolls to the top-left corner of the window and the contents of the screen buffer are set to blanks using the current foreground background colors.

Examples

The following example uses the clear method to clear the console before it executes a loop, prompts the user to select a foreground and background color and to enter a string to display. If the user chooses not to exit the program, the console's original foreground and background colors are restored and the Clear method is called again before re-executing the loop.

#include <xtd/char32_object>
#include <xtd/console>
#include <xtd/startup>
 
using namespace xtd;
using namespace xtd::collections::generic;
using namespace xtd::collections::specialized;
 
namespace console_clear_example {
  class program {
  public:
    // The main entry point for the application.
    static auto main(const string_collection& args) {
      // Save colors so they can be restored when use finishes input.
      auto dft_fore_color = console::foreground_color();
      auto dft_back_color = console::background_color();
      auto continue_flag = true;
      console::clear();
      
      do {
        auto new_fore_color = console_color::white;
        auto new_back_color = console_color::black;
        
        auto fore_color_selection = get_key_press("Select Text Color (B for Blue, R for Red, Y for Yellow): ", list<char32_t> { 'B', 'R', 'Y' });
        switch (fore_color_selection) {
          case 'B':
          case 'b': new_fore_color = console_color::dark_blue; break;
          case 'R':
          case 'r': new_fore_color = console_color::dark_red; break;
          case 'Y':
          case 'y': new_fore_color = console_color::dark_yellow; break;
        }
        
        auto back_color_selection = get_key_press("Select Background Color (W for White, G for Green, M for Magenta): ", list<char32_t> { 'W', 'G', 'M' });
        switch (back_color_selection) {
          case 'W':
          case 'w': new_back_color = console_color::white; break;
          case 'G':
          case 'g': new_back_color = console_color::green; break;
          case 'M':
          case 'm': new_back_color = console_color::magenta; break;
        }
        
        console::write_line();
        console::write("Enter a message to display: ");
        string text_to_display = console::read_line();
        console::write_line();
        console::foreground_color(new_fore_color);
        console::background_color(new_back_color);
        console::write_line(text_to_display);
        console::write_line();
        if (char32_object::to_upper(get_key_press("Display another message (Y/N): ", list<char32_t> { 'Y', 'N' })) == 'N')
          continue_flag = false;
          
        // Restore the default settings and clear the screen.
        console::foreground_color(dft_fore_color);
        console::background_color(dft_back_color);
        console::clear();
      } while (continue_flag);
    }
    
  private:
    static char32_t get_key_press(const string& msg, const list<char32_t>& valid_chars) {
      auto key_pressed = console_key_info {};
      auto valid = false;
      
      console::write_line();
      do {
        console::write(msg);
        key_pressed = console::read_key();
        console::write_line();
        if (std::find(valid_chars.begin(), valid_chars.end(), char32_object::to_upper(key_pressed.key_char())) != valid_chars.end())
          valid = true;
          
      } while (!valid);
      return key_pressed.key_char();
    }
  };
}
 
startup_(console_clear_example::program::main);

The example relies on a get_key_press method to validate the user's selection of a foreground and background color.

Examples

This example demonstrates the cursor_left and cursor_top properties, and the set_cursor_position and clear methods. The example positions the cursor, which determines where the next write will occur, to draw a 5 character by 5 character rectangle using a combination of "+", "|", and "-" strings. Note that the rectangle could be drawn with fewer steps using a combination of other strings.

#include <xtd/console>
 
using namespace xtd;
 
auto orig_row = 0;
auto orig_col = 0;
 
void write_at(const string& s, int x, int y) {
  console::set_cursor_position(orig_col + x, orig_row + y);
  console::write(s);
}
 
auto main() -> int {
  // Clear the screen, then save the top and left coordinates.
  console::clear();
  orig_row = console::cursor_top();
  orig_col = console::cursor_left();
  
  // Draw the left side of a 5x5 rectangle, from top to bottom.
  write_at("+", 0, 0);
  write_at("|", 0, 1);
  write_at("|", 0, 2);
  write_at("|", 0, 3);
  write_at("+", 0, 4);
  
  // Draw the bottom side, from left to right.
  write_at("-", 1, 4); // shortcut: write_at("---", 1, 4)
  write_at("-", 2, 4); // ...
  write_at("-", 3, 4); // ...
  write_at("+", 4, 4);
  
  // Draw the right side, from bottom to top.
  write_at("|", 4, 3);
  write_at("|", 4, 2);
  write_at("|", 4, 1);
  write_at("+", 4, 0);
  
  // Draw the top side, from right to left.
  write_at("-", 3, 0); // shortcut: write_at("---", 1, 0)
  write_at("-", 2, 0); // ...
  write_at("-", 1, 0); // ...
  //
  write_at("All done!", 0, 6);
  console::write_line();
}
 
// This code produces the following output :
//
// +---+
// |   |
// |   |
// |   |
// +---+
//
// All done!