Using the \b escape character in C for a simple counter

counter.c

#include <stdio.h>

//Compile with: $cc counter.c
//run with ./a.out

main(){
	int i;
	for (i = 0; i < 10; ++i){
        //The \b is a lesser known escape character that moves the cursor back one. Allowing you to overwrite what you've previously written.
		printf("\b%i",i); 
        //printf buffers it's output, so when the sleep timer hits, the input is still in the buffer. 
        //You need to flush stdout in order to see the change each iteration otherwise you'll just see 9 on execution
        fflush(stdout); 
        sleep(1);
	}
}