C＃if语句不要做某事

Question

如果“across”或“down”小于或等于零，我正在尝试写if语句以不绘制任何内容。不太明白如何写它来停止draw_rect。虽然我已经放下了= 0

，但仍然有问题

int horiz;
int vert;
int across;
int down;

char display_char;

void draw_rect ( void ) {

    //      If either of the width or height is less than or equal to zero,
    //      the function must not draw anything.


    draw_line( horiz, vert, across, vert, display_char );
    draw_line( horiz, down, across, down, display_char );
    draw_line( horiz, vert, horiz, down, display_char );
    draw_line( across, vert, across, down, display_char );

    if ( down > 0 ){
       ?????
    }   

int main( void ) {
    setup_screen();

    // draw a box.
    horiz = rand() % screen_width() / 2;
    vert = rand() % screen_height() / 2;
    across = 1 + rand() % (screen_width() - horiz - 1);
    down = 1 + rand() % (screen_height() - vert - 1);
    display_char = '@';
    draw_rect();
    show_screen();

    // draw a box with zero height.
    horiz = rand() % screen_width() / 2;
    vert = rand() % screen_height() / 2;
    across = 1 + rand() % (screen_width() - horiz - 1);
    down = 0;
    display_char = 'a';
    draw_rect();
    show_screen();




    timer_pause(5000);
    cleanup_screen();
    return 0;
}

Answer 1

这很简单：

void draw_rect ( void ) 
{

//If either of the width or height is less than or equal to zero,
//the function must not draw anything.

   if(across > 0 && down > 0)
   {
      draw_line( horiz, vert, across, vert, display_char );
      draw_line( horiz, down, across, down, display_char );
      draw_line( horiz, vert, horiz, down, display_char );
      draw_line( across, vert, across, down, display_char );
   }
}

反过来想想它。