C ++ [comma operation]

The comma operation is a relatively small operation.

 

The form of a comma expression is as follows:

Expression 1, expression 2, expression 3,..., expression n

Essentials of a comma expression:

(1) The comma expression is calculated from left to right. That is, its entire value is the value of the last expression.
(2) The comma expression is used as a whole, and its value is the value of the last expression (that is, expression n.
(3) The priority of the comma operator is not the lowest among all operators.

Example:

I = (a = 2*3, a * 5), a + 6;

Result: I = 30

Analysis:

A = 2*3, a * 5 is a comma expression, and the calculated value is 30. I = (a = 2*3, a * 5) constitute an assignment statement, the value assignment statement and a + 6 constitute a comma statement.

 

Similarly, you can analyze the following results ~

I = (a = 2*3, a * 5), a + 6 );

Result: I = 12