How to Convert Bitcoin Cash Address From Old to New Format and Back Using C#

Bitcoin Cash recently switched to a new address format called CashAddr and so did many services and wallets in order to avoid confusion and loss of precious coins.
Yet, the official client doesn't support a conversion between old and new formats.
There are services which address this issue:

• cashaddr.org
• cashaddr.bitcoincash.org
• cashaddress.github.io

And libraries for JS, python and C#.

Using C# library it is one line solution:

Credit goes to the library SharpCashAddr.