3 Operators & Flow Control

Question 1

Arthematic operators in C?

Answer 1

Question 2

% operator in C?

Answer 2

A%B

remainder of the integer division of a/b

Question 3

Microprocessor arithmetic problems?

Answer 3

Most simple processors cannot perform single instruction division or multiplication

Using the PIC, the XC8 compiler will break your maths down into multiple instructions, your code may no longer be deterministic!

Question 4

Arithmetic: Repeat?

Answer 4

Division: Repeated Subtraction

Multiplication: Repeated Addition

Comments: Non-deterministic

Question 5

What can it mean to be non-deterministic?

Answer 5

This means that it can exhibit different results for the same set of data. (Can be unaccurate)

Question 6

Arithmetic: Shift?

Answer 6

Division: Right Shift

Multiplication: Left Shift

Comments: Only for powers of 2

Question 7

Arithmetic: Newton Raphson?

Answer 7

Division: Newton Raphson

Multiplication: -

Comments: very fast, not accurate

Question 8

Arithmetic: Shift +?

Answer 8

Division: -

Multiplication: Lift shift and add

Comments: Only for constants

Question 9

C operator procedure?

Answer 9

• Expressions are usually evaluated from left to right (associativity)
• If an expression has different operators then precedence rules are applied
• Brackets may be used to form sub-expressions that override precedence
• For example arithmetic operators * / will be evaluated before + or – (think BIDMAS)

Question 10

How does C deal with Boolean variables?

Answer 10

• Unlike some other languages C does not have a Boolean type
• C uses int
• Any non-zero value is interpreted as TRUE
• Zero is interpreted as FALSE

Question 11

Relational operators in C?

Answer 11

Question 12

Log Op: AND?

Answer 12

&&

Question 13

Log Op: OR

Answer 13

||

Question 14

Log Op: logical negation?

Answer 14

!

Question 15

Logical negation?

Answer 15

(NOT Gate)

Question 16

True/False?

Answer 16

Question 17

Examples of Logical operators?

Answer 17

Question 18

What are bitwise operators?

Answer 18

Operate on the individual bits of each variable, rather than the variable as a whole

Question 19

Bitwise operators in C?

Answer 19

Question 20

a=5

b=3

c = a&b?

Answer 20

Bitwise AND

a = 5(0b101)

b = 3(0b011)

c = 1 (0b001)

Question 21

a = 5

b = 3

c = a | b

Answer 21

Bitwise OR

a = 5(0b101)

b = 3(0b011)

c = 7 (0b111)

Question 22

a=5

b=3

c = ~a

Answer 22

Operation: Complement.

a = 5 (0b101)

b = 3 (0b011)

c = 250 (0b1111 1010)

Question 23

a =5

b=3

c = a << 2

Answer 23

Operation: Left Shift (*2)

a = 5 (0b101)

b = 3 (0b011)

c = 20 (0b10100)

Question 24

a= 5

b = 4

c = a >> 2

Answer 24

Operation: Right Shift(/2)

a = 5 (0b101)

b = 3 (0b011)

c = 1 (0b001)

Question 25

Bit-wise operators: AND?

Answer 25

&

Question 26

Bit-wise operators: EX-OR

Question 27

Bit-wise operators: OR

Answer 27

|

Question 28

Bit-wise operators: complement

Answer 28

~

Question 29

Bit-wise operators: shift left?

Answer 29

<<

Question 30

Bit-wise operators: shift right

Answer 30

>>

Question 31

The difference between bitwise and Logical?

Answer 31

Question 32

What is Non-linear execution?

Answer 32

• Non-linear execution is caused by an instruction that modifies the Program Counter.
• For example (in assembly): goto, call, btfss, btfsc
• In C there are many instructions that cause non-linear execution,

Question 33

Instructions that cause non-linear execution in C?

Answer 33

Question 34

Example of conditional code in C?

Answer 34

Question 35

Example of loop structure in C?

Answer 35

Question 36

Example of a nested loop in C?

Answer 36