Double and Single quotes.

Question

Whats the differences between them? A symbol and a string?

Answer 1

Double is Double precision floating point number. 64bit floating number.

Sigle quotes are used to express charactor. The type is char.
'a'
If you write multiple characters in it, the type is int.

Answer 2

Single quotes define a character
Double quotes define a string, which is an array of characters.