A forced conversion of data base types, an understanding of automatic conversion

When you encounter data transformations, it is always easy to ignore the conversion between the data and whether you can get the correct results. The summary is as follows: 1. Automatic promotion to large range in small scope

Different types of data are generally automatically promoted in small areas toward a wide range of directions. It can be understood that a large range of precision is larger than a small range, or the number of digits is more.

such as Byte b=3; B=b+2 will complain because 2 is of type int. Cannot force down to byte type.

and Byte b=3; int a=b+1; The result a=4 is obtained because the B is automatically promoted to the int type; 2. Large scale to small range casts

To revert back to the byte type, a cast is required.

such as Byte b=3;  B= (byte) b+1; Of course, if the results overflow must be an error. 3. Automatic conversion (more interesting and characteristic, also relatively easy to overlook)

Mentioned earlier, short s=5; S=s+3 is a wrong type of report. And s+=3 will get the result s=8;

This is because the computer sees S+=3 as s= (the type of data on the left) s+3. And get the right results.

This example is usually assigned to the right.