Class 8 – Conditional Logic

Agenda

Lateral Thinking Warm-up Review Pseudocode & Flowchart Basics Discuss Conditions for Decisions Develop Notation for Conditions Develop Algorithms Incorporating

Conditions Write Code to Accommodate Conditions Project Work

Pseudocode Review

Pseudo-code is structured English that states the steps to the problem solution

1. Statements are written in simple English

2. Each instruction/step is written on a separate line

3. Keywords and indentation are used to signify particular control structures

4. Each set of instructions is written from top to bottom, with only one entry and one exit

Pseudocode in Programs

Start Program

# Prompt for Assignment Name

# Get Assignment Name and assign to variable

# Loop through Students 1-12

# prompt for grade

# get grade and assign to variable

# End Loop

Flow Chart Notation Review

Terminal symbol- indicates the starting or stopping point of logic:

Input/Output symbol- reading orwriting input/output:

Process Symbol- any single process, such as assigning a value or performinga calculation:

Decision Symbol- comparisons/ T or F decision:

Flowlines- connect symbols in the flowchart: arrow head suggests flow of data a straight line may be used to indicate a relationship

Sample FlowChart

Pseudocode# Start Program

#Prompt for assignment

#Set a counter#Loop through grades

# Get student grade# Increment counter

#End loop#Calculate Average#Print Average

# End Program

start

end

Assignment name?

Set counter = 1

Counter>10?

Calculate Average

Print Average

Increment Counter

Student Grade? Ye

sNo

Conditions

Example: Input: 2 integers Choose result type: sum, difference,

product, quotient, modulus, or exponent Processing:?

Conditional Operators Relational Logical

Relational Operators

How does one item relate or compare to another? a>b a<b a=b a<>b a>=b a<=b

Considera=12b=43What is the effect on each of the conditions?

Relational Operators

How does one item relate or compare to another? a>b a<b a=b a<>b a>=b a<=b

Considera=12b=43What is the effect on each of the conditions?

false true false true false true

Logical Operators

For complex conditions AND OR NOT A AND B A OR B NOT A A OR NOT B

Considera=Today is Tuesdayb=It is RainingWhat is the effect on each of the conditions?

Exercise 8-1

Handout Evaluate Conditional Operators

Excel solutions

Branching (Flow Control)

Single Condition if - then

Dual Condition if – else – end if

Multiple Condition select/ case

Notation - Single

PseudocodeSTART

Prompt for inputGet input xIf x>4 then

Display “Hurray”

End if

END

Flowchart

start

end

x>4?

get x

Print “Hurray”

T

F

Notation - Dual

PseudocodeSTART

Prompt for inputGet input xIf x>4 then

Display “Hurray”

elseDisplay “Sorry”

End if

END

Flowchart

start

end

x>4?

Get x

Print “Hurray”

Print “Sorry”

T F

Notation – Multiple (Pseudocode)# START

#Prompt for input#Get input x#Evaluate (Case for x)

# where x= 3#print “close”

# where x= 2#print “very close”

# where x= 1#print “bang on”

# where x is anything else#print “not even

close”

#End case# END

Notation – Multiple (Flowchart)

start

end

X=3

Print “very close”

T

Feval x X=2

Get x

X=1

Print “close”

Print “bang on”

Print “not even

close”

T T

F F

Case versus Nested IF

STARTPrompt for inputGet input xCASE FOR X case x= 3

print “close”case x= 2 print “very close”case x= 1 print “bang on”case other print “not even close”

END CASEEND

STARTPrompt for inputGet input x

if x= 3 print “close”else if x= 2 print “very close” else if x= 1 print “bang on” else print “not even close” end if

end if end if

END

Exercise 8-2

Handout Develop Pseudocode and Flowchart

Conditional Code in Ruby

Conditionals Relational

a>b, a<b, a<=b, a>=b, a==b, a!=b Logical

&& (AND), || (OR), ! (NOT) Requires parenthesis E.g. if (A>6 && C!=“Math”)…

Ruby Demo

Quest: Project Work

Rubric 1. Application Interface is simple and

functional (6) 2. Application functions all work with

appropriate and intuitive prompts (8) 3. Application presents an attractive

output and then exits cleanly without any errors. (6) (hint: pseudocode will allow me to substitute for any lost marks)

Project Work

Total value=20% Due by start of class next

week Prefer you zip the file and

email to me Otherwise I’ll copy it to my flash

disk at start of class

Summary

Review Notation Pseudocode and flowcharts Conditional logic

Relational operators Logical operators

Branching/ Flow Control Ruby language Project evaluation

Questions?

Enjoy the holiday Lest we forget…