3-1 arithmetic operators
% The remainder operator requires that both the left and right sides are integer types, otherwise an error will occur.
3-2 eye
For example 1 + 2 :
+ Is called an operator, and 1 and 2 are called operands. The number of operators depends on how many operands there are.
3-2 Expression
The expression that connects operands with operators and parentheses is called an expression.
1 + 1
'a' + 'b'
a + b
a + 'b' + pow(a,b) * 3 / 4 + 5