refreshing line?

[alexnb185]

I have no clue if this is even possible using C, but it was worth asking. What I want to do is have a number refresh itself ( think of a countdown and the number keeps changing ). A perfect example is if you have two operating systems on your pc, and when you boot if will say select which one you want to boot and if gives you like 15 seconds or w/e to choose. I just want to print a line and have a number in it and have the number countdown or count up or w/e I want the number to do. Does this make since to anyone? If anyone knows if this is possible or how to do it please help!!

[robatino]

Use the backspace character \b. For example,

#include <stdio.h>

int main(void) {
  unsigned int i, j;
  for (i=0; i < 1000000000; ++i) {
    j = printf("&#37;u", i);
    while (j--) printf("\b");
  }
  return 0;
}

[alexnb185]

ok what does j = if it is = to printf().. that is new to me? I know you could make something equal to a function that returns a number or something... is that what this is doing?

[matsp]

Yes, printf returns the number of chars that it printed.

--
Mats

[alexnb185]

oh really.. hah good to know... so for example if I did this

int i;
i = printf("Bob");

That would make i equal to 3????
or four because of the nulll???

[MacGyver]

Try it. Three. printf() doesn't actually print the null char.

[brewbuck]

Use the backspace character \b.

Another method is to use the carriage return character '\r'. This moves the cursor back to the beginning of the line. This doesn't CLEAR the line, however, so you need to write a sufficient number of spaces in order to "blank out" anything that was already there.

Neither character is guaranteed to cause a buffer flush, so if you want to see the results immediately, be sure to fflush(stdout) after printing your data.

[alexnb185]

oh ya don't numbers not have a null or something( I am fairly new to C.... ha). But lets say I was trying to do the same concept only with a 3 letter word, would I have to do that same thing only like put the printf("\b"); four times.. such as this.... ???

printf("\b\b\b\b");

[alexnb185]

could someone also explain to me what the fflush() does exactly and why the buffer needs to be flushed?... I hate to be just a pain but I need to learn somehow...

[ssharish2005]

FAQ will answer your question.

ssharish2005

[Salem]

Did you attempt to read the manual page for fflush() in the 4 minutes it took for you to reply?

[alexnb185]

ya.. I actually did, and it made no sense to me... so don't get all ........y... it isn't like I asked you specifically to help me