Data type conversions in Objective-c

The general principle is that small storage capacity data types can be automatically converted into large storage-capacity data types, depending on the type of data consumed and the type conversion or coercion.

Different types of data are automatically converted from left to right (from low to high) in relation to the following.

_bool, char, short int, enum type-> int->long int->long long-> float-> double-> long double.

If these data types are mixed, the different types of data in the operation are first converted to the same type, and then the conversion is done automatically from left to right, as shown in table 2-3.

Table 2-3 sequence table of type conversions

Operand 1 type	Operand 2 Type	Converted Type
_bool, char, short int, enum type	Int	Int
_bool, char, short int, enum type, int	Long int	Long int
_bool, char, short int, enum type, int, long int	Long Long	Long Long
_bool, char, short int, enum type, int, long int, long long	Float	Float
_bool, char, short int, enum type, int, long int, long long, float	Double	Double
_bool, char, short int, enum type, int, long int, long long, float, double	Long double	Long double