UNIT 2_ programmingflow diagrams

exercises

Technologies 1 ESOgabriela-teacher.blogspot.com

WHAT’S A FLOW DIAGRAM?

A flow diagram is a graphicrepresentation of a sequence.

The flow diagram of a programis the graphic representationof the sequence of actionsthat the computer performswhen we run the program.

This is a very complex example of a flow diagram

EXERCISES

In the next slides, you’ll read a different proposalsof sequences of programs.

You will work cooperatively to work out the flowdiagrams of those sequences. You have to use the symbols we’ve studied in class

Then, you’ll see the solutions and the teacher willexplain.

This is also useful when you study at home.

PROGRAM 1

When the program starts, the computer asks theuser for two numbers (a and b).

The user enters the two numbers, the computeradds them up, and shows the user the result…

What’s this program flowdiagram???

START

END

COMPUTER

OUTPUTS

MESSAGE: “Write

two numbers”

USER INPUTS

two numbers

a, b

COMPUTER ADDS

a + b = c

COMPUTER

OUTPUTS : “The

result is c”

PROGRAM 2

This program is a game. When the game starts, thecomputer asks the user their age.

If the user is under 18, the computer says “Sorry, youcan’t play” and the game closes.

If the user is over 18, the computer says “Welcome”, the first level opens and the user plays. After 20 minutes, the game closes automatically.

What’s this program flow diagram???

START

END

COMPUTER

OUTPUTS

MESSAGE: “How

old are you?”

USER INPUTS

age (a)

GAME OPENS

COMPUTER OUTPUTS :

“Sorry, you can’t play”

a > 18 ?yes

noCOMPUTER

OUTPUTS: “Welcome”

Wait 20 minutes

PROGRAM 3

A program that asks the user for two differentnumbers.

When the user enters the two numbers, thecomputer compares them and tells the userwhich is the highest number.

What’s this program flowdiagram???

START

END

COMPUTER

OUTPUTS

MESSAGE: “Write

two different

numbers”

USER INPUTS

a, b

a > b ?yes

noCOMPUTER

OUTPUTS: “a is the

biggest number”COMPUTER

OUTPUTS: “b is the

biggest number”

PROGRAM 4 A program that asks the user for two different

numbers.

When the user enters the two numbers, thecomputer first makes sure the numbers are different.

If they are the same, it asks the user again.

If they are different, it compares them and tells theuser which is the highest number.

What’s this program flowdiagram???

START

END

COMPUTER

OUTPUTS

MESSAGE: “Write

two different

numbers”

USER INPUTS

a, b

a = b ?yes

no

COMPUTER

OUTPUTS: “a is the

biggest number”

COMPUTER

OUTPUTS: “b is the

biggest number”

a > b ?yes

no

REAL LIFE SITUATION 1The sequence of steps when you find out that a

lamp doesn’t work.

What’s this situation flowdiagram???

START:

Lamp

doesn’t

work

END 1:

PROBLE

M

SORTED!

no

yes

no

Is it

plugged

in?

yes

PLUG IN

Is the bulb

burned out?

Does it

work

now?

no

yes

CHANGE

BULB

REPAIR

LAMP

Does it

work

now?

yes

no

Does it

work

now?

yes

END 2:

Buy a new

lamp

no

EXTRA WORKIf you want to learn more, you can try to design the

flow diagrams of these programs:

PROGRAM 5 An app that ask the user for a password. The app checks if the password is correct. Ifnot, ask the user to re-write it. If it’s correct, the app opens. The maximum number of tries theuser has is 3. After 3 failures, the app closes saying “Sorry, try again later”.

REAL LIFE SITUATION 2 Your home is at walking distance from school, but you prefer to wait for thebus. When you arrive to the bus station, you only take the bus if it’s right there or if it’sapproaching the bus stop. If you can’t see the bus, you walk to school.

PROGRAM 6 A program that asks the user for a number. If the number is higher than 10, theprogram divides the number per 10 and shows the result. If the number is lower, the computersays “Sorry, you number must be higher than 10” and ask the user for a number again.

REAL LIFE SITUATION 3 The sequence of actions you perform in a normal school afternoon between6 pm and 9 pm.