[C Language] -- tips for pairing case and break under Switch

In the C trap and defects, we can see that there is a small trick when the switch statement is used to implement the four arithmetic operations of two numbers. As we all know, break must be added after the case statement, which is worth noting. See the followingCode:

1: subtraction; 2: addition; 3: Division; 4: Multiplication

Switch (FLAG)

{

Case 1: y =-y; // There is no break here;

Case 2: z = x + y; break;

Case 3: y = 1/y; // There is no break here; assume that 1/Y is a score;

Case 4: z = x * Y; break;

}

However, this can also implement the four arithmetic operations of two numbers.