Flowcharts and pseudocode

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Flowcharts

A flowchart is a diagram of an algorithm. Standard symbols: terminator (rounded box, start/end), process (rectangle), decision (diamond, with yes/no or true/false branches), input/output (parallelogram) and arrows showing flow.
Rules: one start, at least one end, one arrow in and out of each process; decisions have two exits.

Read, test and report

Pseudocode

Pseudocode is a structured, language-independent way to write algorithms. It is not a real language but uses programming-like keywords such as INPUT, OUTPUT, IF ... THEN ... ELSE ... ENDIF, WHILE ... ENDWHILE, FOR ... NEXT.
Example: age = INPUT; IF age ≥ 18 THEN OUTPUT "Adult" ELSE OUTPUT "Minor" ENDIF.

Planning with pseudocode

Converting between forms

Translate the algorithm’s meaning, not just its appearance: decision nodes can express IF branches or loop conditions.
A loop-back edge indicates repetition. Preserve initialisation, the condition, updates and both possible exits when changing representation.

Algorithm representations

Trace tables

A trace table records the values of variables as an algorithm runs, showing the output and helping to find logic errors.

Why use them?

They help plan before coding, communicate with others and test logic.

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Practice questions

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1.What is a flowchart?
Easy
- Aa diagram showing the steps of an algorithm
- Ba type of program
- Ca database
- Da network
2.What is pseudocode?
Easy
- Aa way of writing algorithms using programming-like statements
- Ba real language
- Ca diagram
- Da hardware part
3.Which symbol marks start and end?
Easy
- Aterminator
- Bdecision
- Cprocess
- Dinput
4.Which symbol is used for a calculation?
Easy
- Aprocess rectangle
- Bdiamond
- Cparallelogram
- Doval
5.What does an arrow show?
Easy
- Athe direction of flow
- Bthe value
- Cthe error
- Dthe end
6.What is the output? total = 3 + 4 OUTPUT total
Easy
- A7
- B34
- C3
- D4
7.What is the output? x = 5 IF x > 3 THEN OUTPUT "big" ELSE OUTPUT "small" ENDIF
Easy
- Abig
- Bsmall
- C5
- Dnothing
8.Using inclusive FOR bounds and a step of one, which header repeats its body five times?
Easy
- AFOR i = 1 TO 5
- BIF i = 5
- CINPUT i
- DOUTPUT i

More questions

9.What is a trace table used for?
Easy
- Atracking variable values as an algorithm runs
- Bdrawing a diagram
- Cstoring data
- Dencrypting data
10.Why use indentation in pseudocode?
Easy
- Ato show the structure clearly
- Bto save memory
- Cto speed up
- Dto hide errors
11.Which keyword ends an IF statement?
Easy
- AENDIF
- BNEXT
- CEND
- DSTOP
12.What does this output? n = 3 WHILE n > 0 OUTPUT n n = n - 1 ENDWHILE
Medium
- A3 2 1
- B0 1 2 3
- C1 2 3
- D3
13.What does this output? total = 0 FOR i = 1 TO 3 total = total + i NEXT i OUTPUT total
Medium
- A6
- B3
- C0
- D123
14.In the binary-decision flowchart convention used here, how many exits does a decision have?
Medium
- Atwo
- Bone
- Cthree
- Dfour
15.Which structure does a loop-back arrow represent?
Medium
- Aiteration
- Bselection
- Csequence
- Dinput
16.Which should come first when writing a flowchart?
Medium
- Aa start terminator
- Ban end terminator only
- Ca decision only
- Dan output only
17.Which is an advantage of pseudocode?
Medium
- Ait is not tied to a particular language
- Bit runs directly
- Cit is faster
- Dit is compiled
18.Trace: a = 2, b = 3. c = a×b. d = c + a. OUTPUT d. What is output?
Medium
- A8
- B6
- C5
- D2
19.What output does this give? x = 10 IF x MOD 2 = 0 THEN OUTPUT "even" ELSE OUTPUT "odd" ENDIF
Medium
- Aeven
- Bodd
- C0
- D10
20.Which problem does a trace table help find?
Medium
- Alogic errors
- Bspelling mistakes
- Csyntax errors
- Dhardware faults
21.Why might you draw a flowchart before coding?
Medium
- Ato plan and check the logic
- Bto avoid testing
- Cto speed hardware
- Dto write comments
22.What is 'selection'?
Easy
- Achoosing between paths using a condition
- Brepeating
- Csteps in order
- Dinput
23.What is 'iteration'?
Easy
- Arepeating instructions
- Bmaking a decision
- Csteps in order
- Doutput
24.What does OUTPUT do?
Medium
- Adisplays a value
- Breads a value
- Cstores a value
- Dends the program
25.What does INPUT do?
Medium
- Areads a value from the user
- Bdisplays a value
- Cends a loop
- Ddefines a function
26.A flowchart uses standard symbols.
Easy
True or false?
27.A binary decision symbol has two labelled outgoing branches.
Easy
True or false?
28.Pseudocode must follow the exact rules of Python.
Easy
True or false?
29.A trace table records variable values.
Easy
True or false?
30.Flowcharts cannot show loops.
Medium
True or false?
31.Which are flowchart symbols?
Medium
- Aterminator
- Bprocess
- Cdecision
- Dinput/output
- Efunction key
32.Which pseudocode keywords are used for loops?
Medium
- AWHILE
- BFOR
- CREPEAT
- DENDWHILE
- EPRINTER
33.Write pseudocode that asks for a number and outputs "Positive" if it is greater than zero, otherwise "Not positive".
Medium

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