S3 SDD - selection statements

Selection statements

Python programming

​Decisions

Real life is full of examples of consequences which occur when you make a decision. For example if you fail to complete maths or computing homework you may be given a detention or the school may contact home.

Similarly if you complete homework regularly to a good standard you would likely receive a star or be nominated for pupil of the month in the department.

​Decisions in programming

A program can also make decisions and perform an action based around a condition being true. It can do this by using a selection statement. The words if and else are used to indicate which action should be performed in the event of a condition being true or false.

​Decisions in programming

All programming languages will support the use of slection statements, they are a commonly used construct.

Fill in the Blanks

If the current score is 62, what is the variable powerUp set to?

​Decisions in programming

The following is an example of a simple IF... THEN ELSE... selection statement. it has been written in the SQA's reference language (this is a language which is similar to pseudocode).

Comparison operators

When coding selection statements in Python the following operators can be used:

​Operator	​Description
​==	Equal to​
​>	Greater than​
​<	Less than​
​>=	Greater than or equal to​
​<=	Less than or equal to​
​!=	Not equal to​

Comparison operators

When coding a selection statement, you must include the following:

Indentation - To indicate what line of code is run if a condition is met.

Colon - To indicate the beginning of a selection statement or loop.

Multiple Choice

Which of the following is used to indicate the beginning of a selection statement?

• semi-colon

• indentation

• hash tag

• colon

Fill in the Blanks

The purpose of this program is to determine whether a pupil has passed a computing science test. A score of at least 50% would result in a pass.

Which operator is missing from the code shown?

Fill in the Blanks

The purpose of this program is to determine whether a person receives a free ticket to a football match. Anyone under the age of 12 can claim a free ticket.

Which operator is missing from the code shown?

Fill in the Blanks

The purpose of this program is to gather a number to be used in a calculation. The number must be a positive integer.

Write the missing half line of code.

Fill in the Blanks

The purpose of this program is to determine whether the user is able to access the members only section of a website. Members can enter using the password "DiamondPass".

Write the missing line of code.