How to make countdown timer print result on single line in C?

Question

I have code here which works as a countdown timer but it prints results on a new line like this:

here is my code:

int timer()
{
        int count;
        count = 10;

        while(count != 0)
        {
                printf("Time: \t%d \n", count);
                count--;
                sleep(1);
        }

        printf("\nCount down timer has expired\n");
        return 0;
}

what I've tried so far is to change \n to \r to print on a single line but it did not work. I'm trying to make it clear the line and print the next number in the line then clear that and print the next one if that makes sense

Try flushing the buffer after each print `printf("Time: \t%d ", count); fflush(stdout);`. Does that work for you? — chux - Reinstate Monica, Jun 02 '20 at 02:44
sort of. it printed like this: Time: 5Time: 4Time: 3Time: 2Time: 1 — mikejosnton, Jun 02 '20 at 02:48
If it prints like that then you missed the space. And if you expect it to print just the number then skip the Time string — Martheen, Jun 02 '20 at 02:50
@mikejosnton The only other space in that string (following `%d`). Regardless console-cursor positioning quickly falls into toolkit land, usually something like ncurses. — WhozCraig, Jun 02 '20 at 02:52
Now its printing like this: 5 4 3 2 1 Count down timer has expired — mikejosnton, Jun 02 '20 at 02:55
@Martheen do you know how I can get it to clear the line and print the next number in the line then clear that and print the next one? — mikejosnton, Jun 02 '20 at 03:01
Does this answer your question? [Erase the current printed console line](https://stackoverflow.com/questions/1508490/erase-the-current-printed-console-line) — Martheen, Jun 02 '20 at 03:06
Carriage return statement worked for my compiler. I'm getting (Time: 10) *clear* (Time: 9) *clear* (Time: 8) ... Just for clarification, are you using Linux systems or Windows? — Rohan Bari, Jun 02 '20 at 03:34
Try with `printf("\rTime: \t%d ", count);` followed by `fflush(stdout);` — Brecht Sanders, Jun 02 '20 at 07:51

score 1 · Answer 1 · answered Jun 02 '20 at 08:19

1

Try changing printf("Time: \t%d \n", count); to printf("Time: \t%d \t", count);

answered Jun 02 '20 at 08:19

Talha Quddoos

556
6
17

pmg · Answer 2 · 2020-06-02T08:30:49.357

Use "\b \b" to clear one character. Imagine you just printed "42": the 1st '\b' moves the cursor back to over the 2, then the space 'clears' that 2, and finally go back again one more space.

    printf("Time: \t");
    while(count != 0)
    {
            printf("%d", count);
            fflush(stdout);
            sleep(1);
            if (count >= 100) printf("\b \b");
            if (count >= 10) printf("\b \b");
            if (count >= 1) printf("\b \b");
            count--;
    }
    printf(" \n");

score 0 · Accepted Answer · answered Jun 02 '20 at 08:47

Try to add fflush(stdout) after using \r in your printf as mentioned by pmg:

int timer()
{
        int count;
        count = 10;

        while(count != 0)
        {
                printf("Time: \t%d \r", count);
                fflush(stdout);
                count--;
                sleep(1);
        }

        printf("\nCount down timer has expired\n");
        return 0;
}

How to make countdown timer print result on single line in C?

3 Answers3