For CSV (string) to array see here: How to read a CSV file with a changing number of columns
Array to string: What would be the purpose of this? It can be done, but the method depends on what you want to achieve.
For CSV (string) to array see here: How to read a CSV file with a changing number of columns
Array to string: What would be the purpose of this? It can be done, but the method depends on what you want to achieve.