C advanced console printing

sammoewel · 10-23-2008, 04:59 AM

Hi all,

i'm writing a program and i would like to change predefined lines in the
printed text in the terminal, without changing the other text...

For example:

Code:

+----------------------------------------------------+
| Connected to 192.168.9.1                           |
|                                                    |
|                                                    |
|                                                    |
|                                                    |
| TEXT                                               |
| Status message                                     |
|                                                    |
+----------------------------------------------------+

Given this picture, i would like to change "TEXT" & "Status message", without changing the position of "Connected to ...".

Is the only way to do this messing with printf("\b"), or are there other
possibilities?

For example, how is the progress bar in ETA printed in the program 'wget' ?

Thanks in advance!

Sam

abolishtheun · 10-23-2008, 05:53 AM

For full screen console graphics, you need ncurses: http://www.gnu.org/software/ncurses/

But for simple wget like progress bars, all you need to do is print a carriage return character (a carriage return \r is like a newline \n except it doesn't go to a newline! you just return to the head of the current line, which is exactly what you want).

Code:

#include <stdio.h>
#include <unistd.h>
int main(){
    int i,j;
    for(i=1;i<=10;i++) {
         printf("%3d ",i);
         for(j=1;j<=i;j++) { 
             printf("=");
         }
         fflush(stdout); // need this because terminal normally buffers 
                         // until there is a newline printed.
         sleep(1);
         printf("\r"); // return to beginning of line
    }
    printf("\n");

    return 0;
}

michaelk · 10-23-2008, 07:00 AM

Another possibility is using escape control sequences.
http://www.termsys.demon.co.uk/vtansi.htm

Most virtual terminals (xterm etc) have the capability to use VT100,VT200 escape sequences commands to control cursor movement as well as text Attributes.

theNbomr · 10-24-2008, 05:36 AM

Quote:

Originally Posted by michaelk

Another possibility is using escape control sequences.
http://www.termsys.demon.co.uk/vtansi.htm

Most virtual terminals (xterm etc) have the capability to use VT100,VT200 escape sequences commands to control cursor movement as well as text Attributes.

Which is what ncurses does, but saves you from dealing with the details of specific terminal types and capabilities.
--- rod

sammoewel · 10-25-2008, 05:14 AM

Ok, we're gonna try to do it using ncurses, thanks for the replies!

ErV · 10-25-2008, 06:31 AM

Quote:

Originally Posted by sammoewel

Ok, we're gonna try to do it using ncurses, thanks for the replies!

Search for ncurses color tutorial. There was a good tutorial somewhere that dealt exactly with terminal coloring. Unfortunatley I saw it quite some time ago and don't remember where it was.