2.2 Problem solving and programming

Question 1

Why are programming constructs used?

Answer 1

to represent the programs control flow

Question 2

Give three constructs of structured programming.

Answer 2

Sequence, branching and iteration

Question 3

What is the programming construct of sequence?

Answer 3

the code is executed line-by line, from top to bottom

Question 4

What is the programming construct of Branching/selection ?

Answer 4

the block of code is run if a specific condition is met.

Question 5

What is the programming construct of iteration?

Answer 5

the block of code is executed a certain number of times or while a condition is met.

Question 6

What are the two types of iteration?

Answer 6

Count- controlled and condition controlled

Question 7

What is Count-controlled iteration?

Answer 7

the iteration is repeated a give number of times

Question 8

What is Condition-controlled

Answer 8

the iteration continues until a specific condition is met

Question 9

What is Recursion?

Answer 9

a programming construct in which a subroutine calls itself during its execution until a stopping condition is met.

Question 10

What are the advantages of Recursion?

Answer 10

reduces lines of code and is less prone to errors

Question 11

What are the disadvantages of Recursion?

Answer 11

its an inefficient use of memory (can cause a stack over) and is difficult to trace

Question 12

What are the two types of error?

Answer 12

Logic and syntax errors

Question 13

What is a Logic error?

Answer 13

when the program works, but not in the intended way, produce an unexpected output

Question 14

What is a Syntax error?

Answer 14

when the rules of the programming language have been broken

Question 15

What is a Scope?

Answer 15

it refers to the section of code in which the variable is available.

Question 16

What are Local variables?

Answer 16

variables that can only be accessed within the block of code in which they were defined.

Question 17

Why are local variables used?

Answer 17

to ensure subroutines are self-contained

Question 18

What are Global variables?

Answer 18

Variables that can be accessed across the whole program

Question 19

What are the drawbacks to using global variables?

Answer 19

they can be unintentionally over written and require more memory as they aren’t deleted.

Question 20

What happens if a local variable has the same name as a global variable?

Answer 20

the local variable will take precedence

Question 21

What is Modular programming?

Answer 21

a programming technique used to split large, complex programs into smaller, self-contained modules.

Question 22

What is a benefit of a modular design?

Answer 22

it makes it easier to divide tasks between a team as each component can be dealt with individually. the components are also more reusable.

Question 23

What is the top-down approach (stepwise refinement)?

Answer 23

the problem is continually broken down into sub-problems, each can be represented as an individual, self- contained blackbox which performs a certain task

Question 24

What are functions and procedures?

Answer 24

named blocks of code that perform a specific task

Question 25

Whats the difference between functions and procedures?

Answer 25

procedures do not have to return a value; functions always return a value

Question 26

What is a parameter?

Answer 26

a value that is passed into a subroutine

Question 27

What two ways can a parameter be passed into a subroutine?

Answer 27

by value or by reference