charAt(int) function to find the character at a specifix index.
Called on: a string
Arguments: the index at which you'd like the character
Returns: the character at the index passed as an argument
String book = "handbook"; book.charAt(4); // 'b' book.charAt(0); // 'h'
If you pass index that's larger than the string is long, you'll get a
String hello = "Hello!"; hello.charAt(29); java.lang.StringIndexOutOfBoundsException: String index out of range: 29