Programming

Question 1

What is a program?

Answer 1

way of encoding algorithm in a precise enough way for computers to understand the instructions

Question 2

What do high level programming languages do?

Answer 2

enable us to write program that are portable across different machines – they are closer to human languages

ie. Snap, Scratch, Python, C++, Java, Racket

Question 3

What does a compiler/interpreter do?

Answer 3

takes a high level language and translates it into something that looks about the same, regardless of which high level language is used

Question 4

What does an assembler do?

Answer 4

translates from Assembly language to Machine Code

Question 5

What is an Assembly language?

Answer 5

specific to a particular computer architecture and operating system

Question 6

What is machine code?

Answer 6

consists of binary or hexadecimal instructions that a computer can respond to directly

Question 7

What is an algorithm?

Answer 7

precise, systematic method for producing a specified result

Question 8

What are the 3 components of an algorithm?

Answer 8

sequencing
selection
iteration

Question 9

What is sequencing?

Answer 9

instructions are executed in the specified order – order matters

• programs will execute exactly in the order that’s given
• if we assign values to variables, they’ll set one value after another, after another

Question 10

What is a mutation?

Answer 10

updating variables, changing oneself (a step)

Question 11

What is selection?

Answer 11

allows algorithm to select which instructions to execute depending on conditions

‘if ____, then ____’
‘if ____, then ____, else ____’
‘if [possibility], then you can ____, otherwise, you must ____’

Question 12

What is iteration?

Answer 12

allows algorithm to repeat instructions

• loop: allows you to do the same thing over and over again, sometimes without a stopping condition, sometimes forever

‘repeat’
‘repeat until…’
‘repeat forever’

Question 13

What are variables?

Answer 13

named storage location for data (named quantities – name + value)

Question 14

Communication in Snap!

What is a broadcast?

Answer 14

sprites can send messages to each other

Question 15

What is iterative design?

Answer 15

engaging in a continuous cycle (design → prototype → evaluate) until you have satisfied user specification

Question 16

Be able to trace through code.

Answer 16

-

Question 17

Describe what a block of Snap! does in English.

Answer 17

-

Question 18

How do you describe a block of Snap! code in English?

Answer 18

• describe code in terms of input and output, and what is being done

use phrases:

• the block consumes…
• it does…
• it produces/displays/reports…

Question 18

What is a bug?

Answer 18

error or flaw in software that makes it produce wrong or unexpected results

Question 19

What is debugging?

Answer 19

process of finding and fixing bugs

• some bugs can allow ‘black hat hacker’ to gain control of computer

Question 20

What are the 3 types of errors that can occur in software?

Answer 20

logical error
syntax error
semantic error

Question 21

What is logical error?

Answer 21

fail to initialize variable, or there’s an ‘off by one’ error – main type

Question 22

What is a syntax error?

Answer 22

incorrectly typed

Question 23

What is a semantic error?

Answer 23

flaw in your understanding of the question

Question 24

Why can flaw/failure in software programs occur?

Answer 24

- program errors that programmers create while coding application (logical, syntax, and semantic errors) - lack of testing due to limited time, or not having skilled testers to thoroughly test application for issues and defects - frequent changes in requirements and miscommunications among clients, business analysts, developers, and testers

Question 25

Describe computer circuitry at the very lowest level.

Answer 25

made of wires, and each wire is either on or off - therefore, the only operations that can be performed at level are those that operate on single-bit values

Question 26

What are single-bit values?

Answer 26

just ones and zeros – ie. just ons and offs

Question 27

What are Boolean functions?

Answer 27

- take Boolean values (true or false) as inputs, and report new Boolean value as output - Boolean operator consumes only one of two values (true or false), and can produce one of two values (true or false)

Question 28

Boolean Operators What value (true or false) would be produced using the 'and' operator? False and False False and True True and False True and True

Answer 28

F F F T

Question 29

Boolean Operators What value (true or false) would be produced using the 'or' operator? False or False False or True True or False True or True

Answer 29

F T T T

Question 30

Boolean Operators When are 'and' operators true?

Answer 30

both blocks in the operator have to be true

Question 31

Boolean Operators When are 'or' operators true?

Answer 31

at least one of the blocks in the operator have to be true