How to animate the command line?

Question

I have always wondered how people update a previous line in a command line. a great example of this is when using the wget command in linux. It creates an ASCII loading bar

Answer 1

The secret is to print only \r instead of \n or \r\n at the and of the line.

\r is called carriage return and it moves the cursor at the start of the line

\n is called line feed and it moves the cursor on the next line In the console. If you only use \r you overwrite the previously written line. So first write a line like the following:

[          ]

then add a sign for each tick

\r[=         ]

\r[==        ]

...

\r[==========]

and so on. You can use 10 chars, each representing a 10%. Also, if you want to display a message when finished, don't forget to also add enough white chars so that you overwrite the previously written equal signs like so:

\r[done      ]