Integer refers to integer type, that is to say, the type of this variable or constant is integer, including positive and negative integers and zero; Character variables refer to 128 characters, which can also be said to be everything in the ASCii table, such as a, b, 1 2;

The integer 1 is a number, while the character'1'is a symbol, and symbols cannot be added or subtracted. For integers, 1+ 1 gets 2, and for characters' 1'+' 1' gets "1".