1. Learning outcomes 5 Developing Code – Using Flowcharts
You must be able to:
use a systematic approach to problem solving and algorithm creation representing those algorithms using flowcharts
explain simple algorithms in terms of their inputs, processing and outputs
determine the purpose of simple algorithms
obtain user input from the keyboard
output data and information from a program to the computer display.
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2. Use a systematic approach to problem solving and algorithm
5 Developing Code – Using Flowcharts
Use a systematic approach to problem solving and algorithm
creation representing algorithms using flowcharts
In previous lessons we have explored data types and structures. This section looks at flowcharts, but to help to reinforce your learning we will also explore the same structures in pseudo-code and a high level programming language in our examples.
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3. 5 Developing Code – Using Flowcharts
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4. 5 Developing Code – Using Flowcharts
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5. 5 Developing Code – Using Flowcharts
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6. Flowcharts 5 Developing Code – Using Flowcharts
Some programmers prefer drawing flowcharts to represent the logic flow; because flowcharts allow programmers to visualise more easily how the program statements will connect. A flowchart is a visual representation of the sequence of instructions. It shows what comes first, second, third and so on. Flowcharts are a good way to show and help us with:
analysis
decomposition and abstraction
designing the structures and constructs of our code
documenting our solutions
managing a process or program.
© Steve Cushing 2016

7. Flowchart disadvantages
5 Developing Code – Using Flowcharts
Flowchart advantages
Flowcharts are a graphical way of writing an algorithm.
They are standardised, so they all agree on the symbols and their meaning.
They are very visual.
Flowchart disadvantages
They are hard to modify and can be time-consuming.
They need special software for symbols, although some software has these built in.
© Steve Cushing 2016

8. 5 Developing Code – Using Flowcharts
When you create a flowchart, you draw geometric shapes that contain the individual statements and that are connected by a flow line. Flow lines signify that there is a flow that passes from one action to an action the arrow points to.
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9. 5 Developing Code – Using Flowcharts
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10. 5 Developing Code – Using Flowcharts
Flow-lines enter the top of the symbol and exit out of the bottom, except for the Decision symbol, which can have flow lines exiting from the bottom or the sides. In flowcharts the START symbol represents the start of a process. The PROCESS symbol is labelled with a brief description of the process carried out by the flowchart. The END symbol represents the end of a process. It contains either END or RETURN depending on its function in the overall process of the flowchart.
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11. Flowcharts help us to follow a logical structure
5 Developing Code – Using Flowcharts
Flowcharts help us to follow a logical structure
Sequential processing
These instructions do the actual data processing in sequence order, such as input, add/multiply/subtract, copy and output.
Decision making
The decision making within the program is the process of comparing or the evaluation of data and making a decision in the program based on the results.
Iteration
Many routines must be repeated a number of times and are accomplished with the help of loops until the desired result is achieved.
© Steve Cushing 2016

12. 5 Developing Code – Using Flowcharts
One of the most confusing things in a flowchart is telling the loops apart from the selections. This is because both use the diamond shape as their control symbol. Whenever possible, flowcharts should read from top to bottom on a page.
In the next few slides we will explore some of the programming structures you have covered in an earlier lesson.
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13. 5 Developing Code – Using Flowcharts
Pseudo-code
Python 3
x ← USERINPUT
x = input()
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14. 5 Developing Code – Using Flowcharts
Pseudo-code
Python 3
OUTPUT x
print(x)
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15. 5 Developing Code – Using Flowcharts
Pseudo-code
Python 3
IF x < 5 THEN
OUTPUT 'Yes'
ENDIF
if x < 5:
print("Yes")
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16. 5 Developing Code – Using Flowcharts
Pseudo-code
Python 3
IF x < 5 THEN
OUTPUT 'Yes'
ELSE
OUTPUT ‘No‘
ENDIF
if x < 5:
print("Yes")
else:
print(“No")
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17. 5 Developing Code – Using Flowcharts
Pseudo-code
Python 3
WHILE x < 5
do_procedure()
ENDWHILE
while x < 5:
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18. 5 Developing Code – Using Flowcharts
Pseudo-code
Python 3
REPEAT
do_procedure()
UNTIL x < 5
while True:
if x < 5:
break
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19. 5 Developing Code – Using Flowcharts
Pseudo-code
Python 3
FOR count ← 1 TO 4
do_procedure()
ENDFOR
for count in range (1,5):
© Steve Cushing 2016