Thread: Clearing single line?

If you're wanting that level of control over a console screen, perhaps it's time to consider
ncurses - Wikipedia, the free encyclopedia

Originally Posted by louieansonng

What I meant to say was print all the lines from line 24 all the way up, while clearing each line. The first line will start from line 24 and end up in line 0, the second from line 24 and going to line 1, and so on.

You almost certainly need a library for that, as Salem suggests, unless there is some simpler way in windows (if you haven't found one by googling, there probably isn't).

Have a look at ncurses, that's the kind of thing used with console apps where you have color and menus & stuff. So it's more work that a single command but you might find it interesting; you have total control over the text console window and can respond to key presses, etc. It's easier than GUI programming but similar in nature.

Originally Posted by louieansonng

Will I be able to compile it like a normal c file? I'm using Dev-C++ and our project specification says that we can do anything we want as long as we can compile it without problems in Dev-C++ compilers.

I don't know. You'll have to download and install the package and follow the directions there; unless there is something weird about Dev-C++ there is no reason it shouldn't work.

Make sure you link properly to ncurses when you compile.

If your program requires ncurses, then your teacher will need ncurses in order to compile it.

You don't need a special library to do some line clearing of the screen, anyway. If you move the cursor to the first char of the row you want to erase, and print out 80 char's of ' ', then the line will be cleared.

To move the cursor you can:

1) include <conio.h> and use gotoxy(x,y) (Which Dev C may not support since it's non Standard).

2) In Windows, you use SetConsoleCursorPosition(), This is an example showing color and moving the cursor:

Code:

#include <stdio.h>
#include <windows.h>
#include <wincon.h>


void Gotoxy(int, int);

int main(void)  {
   int x, y;
   
   char *starlight = "Oh Be a Fine Girl Kiss Me";
   char *ilike = "I like blue stars";
   for(x = 0, y = 1; x < 41;)  {
      Gotoxy(x,y);
	  printf("%s", ilike);  
	  x += strlen(ilike)+1;
	  
   }
   SetConsoleTextAttribute(GetStdHandle(STD_OUTPUT_HANDLE), FOREGROUND_INTENSITY | FOREGROUND_BLUE | BACKGROUND_RED | BACKGROUND_BLUE |BACKGROUND_GREEN);	
   printf("\n%s\n ", ilike); 
   for(y = 4, x = 10; y < 18; y+=5)  {
      Gotoxy(x, y);
      printf("%s", starlight); 
      SetConsoleTextAttribute(GetStdHandle(STD_OUTPUT_HANDLE), FOREGROUND_INTENSITY | FOREGROUND_GREEN | FOREGROUND_BLUE |  FOREGROUND_RED | BACKGROUND_RED);
   }
   SetConsoleTextAttribute(GetStdHandle(STD_OUTPUT_HANDLE), FOREGROUND_INTENSITY|FOREGROUND_GREEN|FOREGROUND_RED|BACKGROUND_BLUE);	
   printf("\n\n\n%s", starlight);
   SetConsoleTextAttribute(GetStdHandle(STD_OUTPUT_HANDLE), FOREGROUND_INTENSITY|FOREGROUND_GREEN|FOREGROUND_RED|FOREGROUND_BLUE|BACKGROUND_BLUE);	
   printf("\n\n");   
   return 0;
}


void Gotoxy(int x, int y) {
   COORD coord;
   coord.X = x;
   coord.Y = y;
   SetConsoleCursorPosition(GetStdHandle(STD_OUTPUT_HANDLE), coord);
}
/*
   RED + GREEN + BLUE = White	
   RED + GREEN = Yellow
   RED + BLUE = Magenta

   GREEN + BLUE = sickly Green
*/

Printing from the bottom up is generally to be avoided, as WhiteFlag noted, above. If you want to start your drawing at the bottom of the page, you can always draw it starting at the bottom of the page, (use a series of newlines to get there), and printing it normally, let it continue to cause the screen to scroll up, as you continue printing your lines, in top to bottom order.

Originally Posted by Adak

You don't need a special library to do some line clearing of the screen, anyway. If you move the cursor to the first char of the row you want to erase, and print out 80 char's of ' ', then the line will be cleared.

That would assume that the console window is always 80 characters wide.

Originally Posted by louieansonng

Yes, our console window is 80 x 25. Maybe I'll follow adak's way of creating lines...I don't want to waste my time doing something that might not work in our teacher's computer. Thanks for all the suggestions.

You can also use the backspace:

Code:

int main() {
	char ray[4] = {8,8,8,0};
	printf("there%s",ray);
	return 0;
}

output:
th

Originally Posted by MK27

You can also use the backspace:

Code:

int main() {
	char ray[4] = {8,8,8,0};
	printf("there%s",ray);
	return 0;
}

output:
th

That code also assumes you're on an ASCII machine.