Problem with ASCII Rotating Cursor (TUI) Animation - c++

Question

I'm trying to create the rotating cursor animation thing.
Each time I compile this I always get a slash (or two) left at the end, and the backspace character does not work. I used two ways to do this: the sleep function and the chrono timer and they worked very similarly and left a slash after spinning, ignoring the backspace character.
This works differently and as expected if I leave out any newline character or manipulator.
void spinningCursor() {
for (int i = 1; i <= 100; ++i)
{
cout << "-" << flush;
this_thread::sleep_for(chrono::milliseconds(10));
cout << "\b" << flush;
cout << "\\" << flush;
this_thread::sleep_for(chrono::milliseconds(10));
cout << "\b" << flush;
cout << "|" << flush;
this_thread::sleep_for(chrono::milliseconds(10));
cout << "\b" << flush;
cout << "/" << flush;
this_thread::sleep_for(chrono::milliseconds(10));
cout << "\b" << flush;
}
}
Or...
void spinningCursor2() {
for (int i = 0; i < 100; i++) {
cout << "-";
cout.flush();
usleep(10000);
cout << "\b";
cout.flush();
cout << "\\";
cout.flush();
usleep(10000);
cout << "\b";
cout.flush();
cout << "|";
cout.flush();
usleep(10000);
cout << "\b";
cout.flush();
cout << "/";
cout.flush();
usleep(10000);
cout << "\b";
cout.flush();
}
}
main function...
int main()
{
spinningCursor();
cout <<"\nHello, World!"<< endl;
spinningCursor2();
cout <<"\nHello, World, Again!"<< endl;
return 0;
}

Answer 1

The output effect is not guaranteed but dividing it into sections might help.
Idea:
#include <algorithm>
#include <chrono>
#include <cstddef>
#include <iostream>
#include <string>
#include <thread>
using namespace std::chrono_literals; // a cumbersome way to be able to write 100ms
// unformatted output of one char, a backspace, flushing and Zzz...
void slow_put(char ch) {
static const auto delay = 100ms;
static const char bs = '\b';
std::cout.write(&ch, 1);
std::cout.write(&bs, 1);
std::cout.flush();
std::this_thread::sleep_for(delay);
}
// newline, but erase the char under it first
void nl() {
std::cout.write(" \n", 2);
}
// proxy ... decorate stuff here (for debugging etc)
void display(char ch) {
slow_put(ch);
}
// enabler to repeat a bunch of sequences
void spinner(const std::string& sequence) {
// execute the display function for one char at a time
std::for_each(sequence.begin(), sequence.end(), display);
}
// example use of the helpers above
void spinningCursorSchema(size_t times) {
static const std::string seq = R"raw(|/-\)raw"; // the pattern to display
while(times--) spinner(seq);
// add more patterns to this schema if wanted
}
int main() {
std::cout << "Spinner: [ ]\b\b";
spinningCursorSchema(100); // run the spinningCursor 100 times
nl(); // erasing newline
}
Edit: A brief explanation:
For every group of functions you called that I felt could be named, "do_this()" or "do_that()" I put them in a function and named them accordingly.
The purpose of this exercice was not primarily for me to find the error in your code but to provide a frame of reference. It's easier to identify/talk about/fix problems when one can say "your do_this() function needs this or that..." or similar. When everything is in one big code block everyone reading it needs to start from zero. A function with a clear name (or a comment to compensate for the poor naming as I did above, "proxy") and only a few lines of code can be reviewed by everyone without much background knowledge about the bigger problem.
In short, I took your code that was specifically created to do one thing and broke it down into a few functions that I used to rebuild something similar to your original idea. By doing that I made it easier to see flaws, talk about design decisions. If a function of 2-4 lines can be reviewed by 10000 people and they don't see a problem, it's very unlikely that that function is the problem (in itself). By building blocks of small functions with a clear purpose, bughunting becomes a lot more available for everyone, not only people deeply involved in the particular problem you're solving.
I now see that I used a function template from <algorithm> that may be unfamiliar: std::for_each. In this case, it could be replaced by:
for(char ch : sequence) display(ch);
Come to think of it, that's even clearer.
If this wasn't the overview you sought, just comment and point out the parts you want to get explained and I'll try again

Answer 2

The backspace character doesn't actually delete the previous character, all it does is move the cursor itself back one "space". It's the combination of backspace followed by writing another character that does the overwrite or "delete" the character.
Also, the backspace only goes as far as the beginning of the current line. Once you have printed a newline you can't go back "up" a line with a backspace.
On Windows you might be able to get better results by using the Windows console functions, and on POSIX systems (like Linux or macOS) maybe VT100 escape codes.