3.3 Algorithms and Programs

Question 1

Algorithm

Answer 1

A series of steps to solve a specific problems.

Question 2

3 methods of defining algorithms

Answer 2

1. Flowcharts
2. Pseudocode
3. Structured English

Question 3

2 advantages of flowcharts

Answer 3

1. Easy to write
2. Easy technique to understand logic

Question 4

2 disadvantages of flowcharts

Answer 4

1. Time Consuming
2. Difficult to show branching and looping

Question 5

3 advantages of pseudocode

Answer 5

1. Forces programmer to think through logic of code before writing
2. Easier to understand the concept of a program.
3. Easier to convert a flow diagram

Question 6

2 disadvantages of pseudocode

Answer 6

1. No accepted standard so varies wildly
2. More difficult to follow logic in comparison to flowcharts

Question 7

structured English

Answer 7

A cross between pseudocode and plain English.

Question 8

Advantage of structured English

Answer 8

Easy for non-programmers to write.

Question 9

2 disadvantages of structured English.

Answer 9

1. No accepted standard so varies wildly
2. Can be difficult to convert to code.

Question 10

variable

Answer 10

A named space in the memory for a single piece of data.

Question 11

constant

Answer 11

A variable except the data can not be changed in the program.

Question 12

two scopes of a variable

Answer 12

• Local
• Global

Question 13

Global variable (2)

Answer 13

Available throughout the program
Can be read /written from any subroutine.

Question 13

2 advantages of local variable

Answer 13

Variable data is only significant in the subroutine is it being used.
Encourages the use of modular programming

Question 13

local variable

Answer 13

Only exists until the subroutine in which it was created.

Question 14

2 advantages of global variable

Answer 14

• Accessible to all the modules in the program e.g. Constants
• You only have to declare it once

Question 15

2 disadvantages of global variable

Answer 15

• Debugging harder as any statement in the code can alter the value.
• Can discourage modular programming

Question 16

parameter

Answer 16

An item of data passed from one subroutine to another.

Question 17

3 techniques to make code readable

Answer 17

1. Indentation
2. Annotation
3. Use of appropriate identifiers

Question 18

two ways of passing a parameter

Answer 18

1. Passing by value.
2. Passing by reference

Question 20

passing by value (2)

Answer 20

The value is passed from one subroutine to another.
If value is changed by the subroutine, the original value is unchanged.