Because I
In a word, i++;+; +Execute when I equals 0, 3, 6, 9; s+=i
That is, s= 1+4+7+ 10, which means that s=22.
Extended data:
Data type keyword
Short: decorated int, short integer data, decorated int can be omitted.
Long: decorated int, long integer data, decorated int can be omitted.
Long long: decorated int, which is a long integer data, and can be omitted.
Signed: modifies integer data and has a signed data type.
Unsigned: decorated integer data, unsigned data type.
Restrict: Used to define and constrain pointers and indicate that pointers are the initial and only way to access data objects.