Programming

Hi,
I wrote a program for Windows environment. It shows a menu to choice some operations to do. Once an operation is done, it cleans the screen with a system("cls") call, and the menu is shown again.

I'd like to just clean half screen, so the program doesn't need to call again the print menu procedure.

I read there was something like this:

Code:

gotoxy(x,y);
clreol();

But I also read it is deprecated?

Is there any function or way to do this in C?

Are there operating systems which system calls allow to do this?

Thanks in advance.

It's not "depreciated" -- C never had it. I don't think Windows ever had it, either. Certain odd compilers like Borland's may have provided it through a nonstandard library and conio.h, and now you're learning what "portable" means.

Fortunately since you're printing to an actual terminal that understands actual escape sequences, nothing prevents you from [url=https://www.unix.com/302356413-post3.html]making your own[/url]. Just print the right characters and your terminal, if capable, should obey it.

[url=http://ascii-table.com/ansi-escape-sequences.php]here's[/url] a table of ASCII escape sequences to help you build on the functions I linked above. To clear a line, for example:

[code]void clearline(void)
{
/* The \r moves it to the beginning of the line */
printf("\r\033[K");
}[/code] Also note you may need to fflush() after calling these functions to make sure they're printed to the screen right when you want them to be, instead of after the next newline you print. Or just fprintf(stderr, "..."); instead of printf("..."); so it'll never buffer -- though you actually want it to buffer for less flicker. If anything you might want to make the buffer bigger -- you could print a whole screenful of stuff in individual bits, then fflush(stdout); to redraw in one whack.

Oh, you're in Windows. We do have a windows section but this isn't it.

The windows system call stuff was just an example to introduce my question.

I've asked if there's a way to do this in C, standard, independently from the os.

Uhm, we can say my question is portable? ;D


However thanks for the linux tip.

EDIT:

Seems I find a way, but I am not sure this is good:

I found an implementation of gotoxy:

Code:

void  gotoXY(int x, int  y) {
COORD CursorPos = {x, y};
HANDLE hConsole = GetStdHandle(STD_OUTPUT_HANDLE);
SetConsoleCursorPosition(hConsole, CursorPos);
}

I put it on an header file and did:

Code:

     int i = 0, j;
     /* some other code here */
     while ( i < n ) /* n stands for number of lines to clear */
     { 
           j = 0;
           while ( j++ < 256 ) putchar(' '); /* 'clean' a line */
           gotoXY(0, i++); /* move to the next line */
     }

The putchars rewrite the stdout buffer, correct?

Is this efficient? If not, how can I do it efficiently?

There is no standard way of doing this in the C language which is OS independent.

... This is Windows code.

Not that we mind helping Windows users, but obviously you are programming in Windows, and to say you're not interested in Windows code then use Windows calls in the next breath is a little odd.

If you want to do it portably, look for a windows implementation of the curses or ncurses library, you can find curses in most places in UNIX. A bit of a pain to use, but portable.

Don't know why but I thought it was just C. I didn't know that was windows code. I'm totally uneducated about that.

I learned there's no "standard" way for this. Which is the answer to my question.

However now I've got a way of doing it both in Windows and Linux environment, and also a hint on how could I do it portably.

So thanks for your time.