A Level Computing#BristolMet Session Objectives#U2 S2 MUST describe the steps of an algorithm using a program flowchart SHOULD explain the data types and.

A Level Computing#BristolMet

Session Objectives#U2 S2

MUST describe the steps of an algorithm using a program flowchart

SHOULD explain the data types and basic program constructs required for a given program

COULD create a simple one function calculator in Javascript

Create a multiple function calculator with end or continue screen.

A Level Computing#BristolMet

Keywords

Selection

Data TypesVariables & Constants

Algorithm Sequence

Iteration

A Level Computing#BristolMet

Planning a programme

Before attempting to write a programme, the solution needs to be planned. This helps the coder to see what they want to achieve and how they can best achieve it by breaking the problem down into logical steps.

Methods for planning a programme solution include the use of the flow charts and pseudocode.

FLOW CHARTS – the following symbols are used

START STOP

Area = Width x Height

Start or Stop a programme

Represent a process i.e adding

Represents input or output values

A decision symbol i.e Yes or No, or a choice of paths

START

STOP

Input Width

Input Height

Output Area

What will this programme do?

A Level Computing#BristolMet

Flow Charts

Simple flow chart with decision symbols.

START

Check the weather outside

Is it raining

?

Wear waterproof

trousers

Don’t wear waterproofsSTOP STOP

IF Yes

Else No

TASK 1: Create a flow chart for making a cup of coffee.

A Level Computing#BristolMet

3 basic program constructs

RECAP:

Can you remember what the 3 basic program constructs are?

Sequence IterationSelectionTASK 2: Prepare to explain the program constructs needed in your coffee program

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Data Types (Variable Type)

In databases we already know that the software needs to know what type of data is being held in each data field. This is known as the field type.

Similarly when writing programs it is necessary to understand the type of data that will be held by the variables used in the program.

The reasons are the same as databases:i) It provides limited validation of dataii) Certain operations can only be performed on certain data types (NB: the

prompt() command in Javascript is set to string therefore it cannot automatically perform mathematical operations )

iii) Memory can be efficiently allocated to store data.

A Level Computing#BristolMet

Data Types (Variable Type)

For this course, the data types you need to know about are:• Integer• Floating Point• Real• Boolean • Character • String

TASK 3: In your course folders, make notes on each type giving examples.

Data Types Resource - Teach-ICT

TASK 4: Prepare to discuss the variable types which could be used for your coffee program.

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Creating a coding solution

TASK 4: Now create a flow chart for a program that will add any two numbers and give the result.

ANSWER:

Answer = N1 + N2

START

STOP

Input Number 1

Input Number 2

Output Answer

PseudocodeDeclare variables for number1, 2 and answer

Prompt input number1 and store as variable

Prompt input number2 and store as variable

Answer of number1 + number2stored as variable

Alert user of answer as message.

A Level Computing#BristolMet

Coded Solution

Now let’s code this solution.Remember javascript goes inbetween <script>…</script> tagsTIPS:Declare variables at the start of the programvar x,var y,

parseInt()This will convert the data type to an Integer. (NB prompts are treated as string)

Var1 = parseInt(prompt(‘Enter something here?’))

Notice the 2 bracketsneeded to close the 2

open bracketsAlert() To display output

A Level Computing#BristolMet

Multiple Function Calculator

TASK 5:

Create a calculator which can perform all 4 maths operations. You must design the solution first by creating a flow chart.

EXT: How could the efficiency of this program be improved??

A Level Computing#BristolMet

Flow Chart for 4 Operations Calculator

Answer = N1 + N2

START

STOP

Input Number 1

Input Number 2

Output Answer

Answer = N1 / N2

STOP

Input Number 1

Input Number 2

Output Answer

Answer = N1 * N2

STOP

Input Number 1

Input Number 2

Output Answer

Answer = N1 - N2

STOP

Input Number 1

Input Number 2

Output Answer

Which Calculator

If = +

If = - If = *

If = /

A Level Computing#BristolMet

Keywords

Selection

Data TypesVariables & Constants

Algorithm Sequence

Iteration