1. Från verkligt problem till Datorprogram?
Du vet vad Du vill göra, men hur kommer man till ett färdigt C-program?

2. Structure diagram By 2IT Data students … Division Time
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Structure diagram
By 2IT Data students …
Division
”Morningwhile has gold in mouthd”
Morning routine
Get dressed
Eat breakfast
Go to school
A strucure diagram is used to divide a problem or activity into smaller parts. These smaller parts can be divided into even smaller parts, and so on.
Time
KTH / 2IT / Data / Anders Sjögren

3. Sequence (order in time)
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Sequence (order in time)
Morning routine
Sequence
Get dressed
Eat breakfast
Go to school
Sequence parts
A sequence describes an activity that can be divided into separate activities, all taking part in a certain order in time.
First… Then… And at last…
Ex: ”Morning routine” is a sequence of three separate activities, sequence parts. The three activities take place from left to right. First you get dressed, then you eat breakfast and at last you go to school.
8:00 am
8:02 am
8:05 am
Time
KTH / 2IT / Data / Anders Sjögren

4. Structure diagram Division Time ”Morningwhile has gold in mouthd”
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Structure diagram
”Morningwhile has gold in mouthd”
Morning routine
Get dressed
Eat breakfast
Go to school
Find clothes
Put clothes on
Take from
wash basket
Ask girlfriend
where clothes are
At the top you see the activity at its whole.
At the bottom you see the same activity in many smaller activities.
Division
Time
KTH / 2IT / Data / Anders Sjögren

5. Selection What colour on your socks? Blue Pink White Selection
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Selection
What colour on your socks?
Selection
Blue
Pink
White
If blue exists
If blue doesn’t exist, but pink does
Else
A selection describes a choice between two or more alternatives.
Example:
When you choose the colour of your socks, you can choose between three different colours. The structure diagram then looks like above.
The selection ”What colour on your socks?” consists of three selection parts: ”Blue”, ”Pink” and ”White”. Selection parts are marked with a ring (O, from the word ”Or”) in the top right corner.
The selection part always comes with a condition. If the condition is fulfilled, the selection part is chosen.
Selection parts
KTH / 2IT / Data / Anders Sjögren

6. Structure diagram Division Time ”Morningwhile has gold in mouthd”
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Structure diagram
”Morningwhile has gold in mouthd”
Morning routine
Take from
wash basket
Ask girlfriend
where clothes are
Find clothes
Put clothes on
Get dressed
Eat breakfast
Go to school
Many glasses of beer
One glass of beer
When you’ve got dressed, it’s time to eat breakfast. Of course, our breakfast in this case consists of ”Many glasses of beer”.
In a structure diagram, ”Many glasses of beer” is equal to ”One beer”, performed many times.
Division
Time
KTH / 2IT / Data / Anders Sjögren

7. Iteration (repetition)
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Iteration (repetition)
Drink beer (lightbeer)
Many glasses of beer
Iteration
One beer
As long as you’re thirsty
An iteration is a repetition of an event.
The iteration ”Many glasses of beer” consists of the iteration part ”One beer”. The iteration part always comes with a condition. As long as the condition is fulfilled, the iteration repeats.
The iteration part is marked with an asterisk (*, the computers multiply sign) in the top right corner of the square.
Iteration part
KTH / 2IT / Data / Anders Sjögren

8. Structure diagram Division Time ”Morningwhile has gold in mouthd”
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Structure diagram
”Morningwhile has gold in mouthd”
Morning routine
Take from
wash basket
Ask girlfriend
where clothes are
Find clothes
Put clothes on
Get dressed
Eat breakfast
Go to school
Many glasses of beer
One glass of beer
Take a cab
Run
One step
Note that, in this structure diagram, you need to ”Get dressed” before you ”Eat breakfast” and do both before you ”Go to school”.
Division
Time
KTH / 2IT / Data / Anders Sjögren

9. F01a-jsp
Flow chart
Move foot one step
Run
Go to school
Eat one pancake
Eat breakfast
Put on the clothes
Ask girl/boyfriend
Get from laundry
basket
Search clothes
Get dressed
Morning route
IF you find basket
WHILE pancakes <> 0
Take a cab
IF money = 0
ELSE
WHILE distance to school <> 0
Flowcharts are onedimensional. They are used when you have to describe exactly how the code is processed.
The Structure diagram is easier to follow.
KTH / 2IT / Data / Anders Sjögren

10. Crossing A B Imagine driving in car B, just behind another car A.
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Crossing
Imagine driving in car B, just behind another car A.
You come to a crossing.
How will you know which direction it will chose?
Two cars positioned in a crossing. The car named ”A” has to choose in which direction it want´s to go. How will the car named ”B” know what the car in front of it will do. Let´s make a structure of the problem. A
Car A has to make a selection B
KTH / 2IT / Data / Anders Sjögren

11. Crossing a selection of directions
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Crossing a selection of directions
How can you see in which direction the car in
front of you will choose?
Selection
Crossing
Green signal
STOP
DRIVE
Red signal
Left blinker
Right blinker
No blinker
Drive left
Straight ahead
Drive right
The car named ”A” have several choies. The choices is depending on what the crossing allows. If the light turns red (condition =”Red signal”) the car must stop. If the light turns green (condition = ”Green signal”) and car ”A” chooses to turn right it will use right blinker (condition = ”Right blinker”). The following car will know by the condition, that car in front of it will turn right.
KTH / 2IT / Data / Anders Sjögren

12. not JSP Marriage - a selection? Young man´s future choice Marry girl
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Marriage - a selection?
Young man´s
future choice
Marry girl
In what way can you not construct a selection in a srutucturediagram? A selection must have two selectionparts, choices, or else it´s not a selection. The picture above has only one choice to made.
This is not correct.
not JSP
KTH / 2IT / Data / Anders Sjögren

13. Like this! Selectionparts Marry girl Young man´s future choice
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Selectionparts
A selection must contain at least two selection components. If It only contains one there is no selection.
Young man´s future choice
Marry girl
Be free!!
Like this!
We see that the same structurediagram now has two selectionparts. It has become a selection. A choice can be made.
This is correct.
KTH / 2IT / Data / Anders Sjögren

14. Al Bundy? Young man´s future choice Marry girl
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Al Bundy?
It is however possible to leave a selection component empty.
We know the end…? Peg.. - make dinner!
Marry girl
Young man´s future choice
This is another example of how you can construct a selection. There is a choice, but nothing happens in one of the selectionparts.
KTH / 2IT / Data / Anders Sjögren

15. not JSP Rules of Christmas Santa Claus X-mas day Checks his slade
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Rules of Christmas
Santa Claus
X-mas day
Checks his
slade
Gives one
gift *
While gifts not 0
How can you not construct an iteration? This example has an iterationpart placed in a sequence.
This is not correct.
not JSP
KTH / 2IT / Data / Anders Sjögren

16. This is CORRECT!! Santa changed his mind Santa Claus X-mas day
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Santa changed his mind
Parts connected to the same component must be of similar type
Santa Claus
X-mas day
Checks his
slade
First
Hands out
gifts
Last
This
is CORRECT!!
Gives one
gift
While gifts not 0 *
The picture has been changed. We placed a sequencecomponent just above the iterationpart. ”Hands out gifts” is an iteration and ”Gives one gift” is the iterating part.
This is correct.
KTH / 2IT / Data / Anders Sjögren

17. Paint house - an iteration
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Paint house - an iteration
Paint
House
Get paint *
While painter not satisfied
with color
Paint with
Brush *
While entire house not painted
This is another way you can not construct an iteration. An iteration must only have one iterating part.
not JSP
KTH / 2IT / Data / Anders Sjögren

18. Now you can begin to paint
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Now you can begin to paint
An iteration can only contain one repeated component
Paint
House
Iterations
Iteration
components
OK !
Get paint
Begin to
paint
Get one
can of paint
Paint with
Brush *
While painter not satisfied
with color
While entire house not painted
Now we see the correct way to describe the example.
KTH / 2IT / Data / Anders Sjögren

19. JSP-editor Henrik Engström JSP-editor
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JSP-editor
Henrik Engström JSP-editor applet.
Henrik Engström JSP-editor
KTH / 2IT / Data / Anders Sjögren

20. F01a-jsp
Generate C
Generate C-code templates to show the the structure of your programs!
KTH / 2IT / Data / Anders Sjögren

21. F01a-jsp
Web-Quiz
Now there are some ”web-questions” you should answer about structure diagrams!
KTH / 2IT / Data / Anders Sjögren

22. Web-Quiz Go on by yourselves! F01a-jsp 2019-05-23
KTH / 2IT / Data / Anders Sjögren

23. Pseudocode
Pseudocode is a compact and informal high-level description of a computer programming algorithm that uses the structural conventions of a programming language, but is intended for human reading rather than machine reading.

24. BubleSort algorithm in psdeudocode
Example of pseudocode …
while not at end of list compare adjacent elements if second is greater than first switch them get next two elements if elements were switched repeat for entire list

25. Lycka till med övningarna!