Enums and bitwise operators

Question 1

How to declare an enum?

Answer 1

enum tag { INT, DOUBLE]

Question 2

How do you initialize an enum?

Answer 2

enum tag { A = 1, B = 2, C, D = -6, F } // Not really initializing

Each of the elements are assigned numbers in increasing order.

By default, the first element will be given 0.

enum tag newtag = A; // initializing

Question 3

How do you print out an enum?

Answer 3

enum tag newtag = INT

printf(“%d”, t); // prints out the number associated with that enum

Question 4

What should you watch out for when naming or tagging a struct, union or enums.

Answer 4

Structs, unions and enums share the same namespace so their names can collide.

Question 5

Where would you use enums inside a struct?

Answer 5

Enums can be used to as a tag to for a struct with a union.

Question 6

• w1 & w2
• w1 | w2

Answer 6

• Bitwise and - mask one value with another
• Bitwise or - merge together 2 values

Question 7

• w1 ^ w2
• ¬ (tilde) w

Answer 7

• bitwise exclusive or between 2 values
• ones complement invert

Question 8

• w &= 0xff
• b |= w & 0xff

Answer 8

• Need to check
• Merge b with the last byte of x ( need to check if it is supposed to be 0xff or something else )