What's the answer for this?

Question

What is the value of mark if the value of grade = 'C' ?

switch (grade) {

case 'A' : mark = 90;

case 'B' : mark = 80;

case 'C' : mark = 70;

case 'D' : mark = 60;

break;

case 'E': mark = 50;

break;

default: mark = 40;

}

a) 40

b) 50

c) 60

d) 70

e) 80

At first I thought the answer would be 70 60 = 130... But the answers do not include 130.. So i guess the answer would be 60.. correct?

Answer 1

Concerning the first problem, yes the answer is indeed 60.

This is how execution would work

--> switch(grade)

--> case 'C': mark=70  // We jump here and set mark to 70

--> case 'D': mark=60 // Even though grade!=D we execute the statement here as well, because no further comparison is performed.

--> break; // Now we leave the switch statement.

This would be the correct code if we wanted to get the right mark for each grade.

switch (grade) {

case 'A' : mark = 90;

break; <-- If this break statement was missing, we would just continue

case 'B' : mark = 80; <-- here

break;

case 'C' : mark = 70;

break;

case 'D' : mark = 60;

break;

case 'E': mark = 50;

break;

default: mark = 40;

}

Operators in Java that have the same precedence are evaluated according to their associativity. Operators that are left-associative are evaluated from left to right, operators that are right-associative are evaluated from right to left. *,/ and % as well as + and - are left-associative. Therefore they are evaluated from left to right.

*, / and % however have a higher precedence than + and - and are therefore evaluated before + and -.

=== Evaluate operators with higher precedence from left to right

9 + 3 % 4 * 3 - 5

9 + 3 * 3 - 5

=== Evaluate operators with lower precedence from left to right

9 + 9 - 5

18 - 5

13

You can find the list of operators, their precedence and their associativity on the site posted below.

EDIT:

No. 3 % 4=3 ( the remainder of 3 / 4)

9 + (3 % 4) * 3 - 5

9 + (3) * 3 - 5