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Single Star

In this program, you'll animate a single asterisk causing it to bounce back and forth from column zero to some column (currently defined as 40).

You'll learn:

  • how to force output to happen even before a new line character
  • how to overwrite a line on the console (rather than advancing to a new line)
  • how to delay your program's execution for a short while (for timing purposes)
  • usage of cinttypes which makes the specific flavor of an integer unambiguous

Write a program that animates a single asterisk like this:

star

Don't worry about the program terminating - just kill it when you're done looking.

No data structure is needed for this program as everything you need to do is based on a counter.

You'll need these include files:

#include <iostream>
#include <iomanip>
#include <cinttypes>
#include <chrono>
#include <thread>

I used the features of iomanip to space out the animating asterisk.

cinttypes contains aliases for integer types that are unambiguous. That is, when you say int, how big is it? Depends. Using cinttypes you can declare:

type meaning without cinttypes
uint8_t unsigned 8 bit integer unsigned char
uint16_t unsigned 16 bit integer unsigned short
uint32_t unsigned 32 bit integer unsigned int
uint64_t unsigned 64 bit integer unsigned long
int8_t signed 8 bit integer char
int16_t signed 16 bit integer short
int32_t signed 32 bit integer int
int64_t signed 64 bit integer long

chrono and thread are used together to implement delays in your program. Without pausing your program, it will update the screen so quickly, you won't be able to enjoy the animation.

For example:

this_thread::sleep_for(chrono::milliseconds(16));

will cause your program to sleep for at least 16 milliseconds but maybe a tad more. The value 16 milliseconds is chosen as it is 1/60th of a second.

Output without new lines

You're used to this:

cout << "Foo" << endl;

The endl is doing two things for you:

  1. Of course, it's giving you a new line but it is also
  2. Triggering the output to actually render on your console

Console output is buffered for efficiency. Actual output only happens when new lines are emitted. In this program, we're not using new lines at all. Instead, after text is output, we'll emit only a carriage return ('\r').

To force output (without a new line), do:

cout.flush();

Source code

DO NOT LOOK AT THIS UNTIL YOU HAVE TRIED TO WRITE THE CODE YOURSELF! With that said, don't feel bad about taking a peek and reading the comments.

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