8. Programming

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Dotted terms are defined in the glossary.

• Hello — INPUT, OUTPUT & arithmetic

  Read a name and an age, then output a sentence built from several values.

  O LevelASPseudocodeBasics & data types §2.4, §5.1
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• The five basic data types

  INTEGER, REAL, CHAR, STRING and BOOLEAN — how each is declared, written and output.

  O LevelASPseudocodeBasics & data types §2.1–2.2
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• Constants & expressions

  CONSTANT for values that never change; brackets and ROUND to control the result.

  O LevelASPseudocodeBasics & data types §2.5, §5.2
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• DIV and MOD — quotient and remainder

  Convert minutes to hours and minutes, then give change using the fewest coins.

  O LevelASPseudocodeBasics & data types §5.2
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• Relational & logic operators

  Every comparison gives TRUE or FALSE; AND, OR and NOT combine them.

  O LevelASPseudocodeBasics & data types §5.3–5.4
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• Converting between types

  NUM_TO_STR, STR_TO_NUM, ASC and CHR — the library routines that move between numbers, strings and characters.

  O LevelASPseudocodeBasics & data types 2210 §8.1 library routines
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• IF … THEN … ELSE

  Pass or fail from a single input.

  O LevelASPseudocodeSelection §6.1
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• Nested IF — grade boundaries

  There is no ELSEIF in Cambridge pseudocode: nest the IFs and close every ENDIF.

  O LevelASPseudocodeSelection §6.1
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• CASE OF — a menu

  One value, many outcomes; OTHERWISE catches everything else.

  O LevelASPseudocodeSelection §6.2
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• CASE with ranges and lists

  Ranges like 5 TO 17 and lists like "Sat", "Sun" on one line each.

  O LevelASPseudocodeSelection §6.2
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• Complex conditions — leap year

  AND, OR and NOT with brackets to make the order of evaluation explicit.

  O LevelASPseudocodeSelection §5.4
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• FOR loop & totalling

  A count-controlled loop that accumulates a running total.

  O LevelASPseudocodeIteration §7.1
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• FOR with STEP

  Count down with a negative step, and count in twos.

  O LevelASPseudocodeIteration §7.1
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• WHILE with a sentinel — totalling & counting

  Read numbers until -1; INPUT once before the loop and again at the end of the body.

  O LevelASPseudocodeIteration §7.3 · 2210 WHILE … DO
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• REPEAT … UNTIL — password with 3 attempts

  A post-condition loop runs at least once; the condition is checked at the end.

  O LevelASPseudocodeIteration §7.2
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• Nested FOR loops — times-table grid

  The inner loop runs completely for every pass of the outer loop.

  O LevelASPseudocodeIteration §7.1
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• The same job with FOR, WHILE and REPEAT

  Count-controlled, pre-condition and post-condition loops side by side.

  O LevelASPseudocodeIteration §7.1–7.3
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• 2210 string routines

  LENGTH, SUBSTRING(start, length), UCASE and LCASE on whole strings — the O Level set.

  O LevelPseudocodeString handling 2210 §8.1
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• Reverse a string

  Walk the string backwards with STEP -1 and build a new one.

  O LevelASPseudocodeString handling §5.5, §7.1
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• Palindrome check

  Lower-case the word, reverse it, compare.

  O LevelASPseudocodeString handling §5.5
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• Count the vowels

  Take one character at a time and test it against a list of values.

  O LevelASPseudocodeString handling §5.5
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• Initials from a full name

  Find each space and take the character after it.

  O LevelASPseudocodeString handling §5.5
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• Word count & longest word

  Split a sentence on spaces without any split function — track the current word as you go.

  O LevelASPseudocodeString handling §5.5
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• Letters, digits or other?

  Compare characters with ranges like 'A' to 'Z' — the basis of format checks.

  O LevelASPseudocodeString handling §5.3
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• Fill a 1D array with INPUT, output it backwards

  Arrays are indexed from 1; a FOR loop visits every element.

  O LevelASPseudocodeArrays §3.1–3.2
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• 2D array — marks table with row and column totals

  ARRAY[1:3, 1:4]: the first index is the row (student), the second the column (test).

  O LevelASPseudocodeArrays §3.1–3.2, §7.1
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• Parallel arrays — names and marks

  Two arrays share an index: Names[i] belongs with Marks[i].

  O LevelASPseudocodeArrays §3.2
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• Frequency count of 600 dice rolls

  The dice value is used directly as the array index — no IF needed.

  O LevelASPseudocodeArrays §5.6
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• Procedures with parameters

  A procedure that draws a line, called by another procedure that draws a triangle.

  O LevelASPseudocodeProcedures & functions §8.1
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• Functions that RETURN a value

  Functions are used inside expressions — never with CALL.

  O LevelASPseudocodeProcedures & functions §8.2
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• Local vs global variables

  A DECLARE inside a procedure makes a new local variable; without one, the global is used.

  O LevelASPseudocodeProcedures & functions 2210 §8.1 / 9618 §11.3
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• Text file — write then read to EOF

  OPENFILE FOR WRITE creates the file; FOR READ plus a WHILE NOT EOF loop reads every line.

  O LevelASPseudocodeFile handling §9.1
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• APPEND to a file & count its lines

  WRITE starts a new file; APPEND adds after the existing data.

  O LevelASPseudocodeFile handling §9.1
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• O Level Section B — a week of temperatures

  Validate seven readings into an array, then report the average and the hottest day. Everything Paper 2 Section B expects in one program.

  O LevelPseudocodeExam-style tasks 2210 §7–8
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• O Level Section B — cinema booking

  Ticket types with CASE, quantities, a running total and a group discount.

  O LevelPseudocodeExam-style tasks 2210 §7–8
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• Hello — input(), print() and f-strings

  Read a name and an age, convert the age with int(), and print a sentence. The Python twin of the first pseudocode example.

  O LevelASPythonBasics & data types §2.4, §5.1 ↔ Python
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• Data types: int, float, str, bool

  Python works out the type from the value — type() shows it. Compare with DECLARE in pseudocode.

  O LevelASPythonBasics & data types §2.1–2.2 ↔ Python
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• Constants (by convention) and rounding

  Python has no CONSTANT keyword — UPPER_CASE names signal a value that must not change. round() controls decimal places.

  O LevelASPythonBasics & data types §2.5 ↔ Python
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• // and % — quotient and remainder

  Minutes to hours and minutes, and change with the fewest coins. // is DIV, % is MOD.

  O LevelASPythonBasics & data types §5.2 ↔ Python
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• Converting between str and numbers

  input() always gives a str. int() and float() convert it; str() goes the other way. The #1 cause of TypeError.

  O LevelASPythonBasics & data types §5.5 NUM_TO_STR ↔ Python
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• if / elif / else — grade boundaries

  elif replaces the nested IF … ELSE … ENDIF of pseudocode. Conditions are checked in order; the first true one wins.

  O LevelASPythonSelection §6.1 ↔ Python
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• match / case — the CASE statement

  Python 3.10+ has match, the closest thing to CASE OF … OTHERWISE. Ranges are written as guards.

  O LevelASPythonSelection §6.2 ↔ Python
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• Boolean conditions — and, or, not

  Leap years and a login check. Note the lower-case and / or / not, and == for comparison.

  O LevelASPythonSelection §5.3 ↔ Python
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• for … in range() — counted loops

  range(1, 6) is FOR i ← 1 TO 5. range(10, 0, -2) counts down. The end value is not included!

  O LevelASPythonIteration §7.1 ↔ Python
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• while — condition-controlled loop

  WHILE … ENDWHILE. Python has no REPEAT … UNTIL: write while True with a break, or test the condition first.

  O LevelASPythonIteration §7.2–7.3 ↔ Python
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• Nested loops — times table

  One loop inside another; end="\t" keeps each row on one line.

  O LevelASPythonIteration §7.1 ↔ Python
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• String handling — len, slicing, upper, lower

  Python strings are indexed from 0. s[i], s[a:b], len(), .upper(), .lower() replace LENGTH, SUBSTRING, UCASE, LCASE.

  O LevelASPythonString handling §5.5 ↔ Python
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• Reverse a string and test a palindrome

  Loop version (exam-style) and the slice trick s[::-1].

  O LevelASPythonString handling §5.5 ↔ Python
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• Count vowels and words

  Character-by-character loop with in, then split() to count words.

  O LevelASPythonString handling §5.5 ↔ Python
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• Caesar cipher with ord() and chr()

  Shift each letter by a key, wrapping round the alphabet with %. Non-letters are left alone.

  O LevelASPythonString handling §5.5 ↔ Python
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• Lists — the Python array

  Create, index, change, append, and loop. Remember index 0. len() gives the size.

  O LevelASPythonArrays §3.1–3.2 ↔ Python
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• 2D list — seating plan

  A list of lists. seat[row][col]. Build it with a comprehension so each row is a separate list.

  O LevelASPythonArrays §3.1 ↔ Python
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• Functions and procedures — def and return

  A procedure is a def with no return; a function returns a value. Parameters are passed by value for numbers/strings.

  O LevelASPythonProcedures & functions §8.1–8.2 ↔ Python
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• Write then read a text file

  open() with 'w', 'a' and 'r'; with closes the file for you. The file appears in the Files panel after the run.

  O LevelASPythonFile handling §9.1 ↔ Python
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• 2210 Section B: marks for a class

  Read 5 marks with validation into a list, then output the average and the highest with the student's name. Typical 15-mark task.

  O LevelPythonExam-style tasks 2210 §8
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• Swap two values

  Three assignments with a temporary variable — order matters.

  O LevelASSequence & I/O 2210 §8.1
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• Grade from a mark (CASE)

  A CASE statement becomes a chain of decisions, each branch to the right.

  O LevelASSelection 2210 §8.1
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• Leap year

  Compound condition with AND / OR in one decision box.

  O LevelASSelection 2210 §8.1
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• Count 1 to 10 (FOR)

  The FOR loop drawn the Cambridge way: set counter, test, body, add one, loop back.

  O LevelASLoops 2210 §8.1
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• Times table

  Count-controlled loop with a calculation in the body.

  O LevelLoops 2210 §8.1
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• Keep doubling (WHILE)

  Pre-condition loop: the test is at the top, so the body may never run.

  O LevelASLoops 2210 §8.1
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• Guess the number (REPEAT)

  Post-condition loop: the decision sits at the bottom, so the body runs at least once.

  O LevelASLoops 2210 §8.1
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• Countdown with STEP −1

  A FOR loop that counts down — the decision becomes >=.

  O LevelASLoops 2210 §8.1
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• Nested loops (grid)

  A loop inside a loop: the inner arrow-back sits inside the outer one.

  O LevelASLoops 2210 §8.1
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• Length check on a password

  LENGTH() inside the decision box; loop until 8 or more characters.

  O LevelASValidation & rejection loops 2210 §8.1
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• Fill an array of 5 names

  The loop counter doubles as the array index.

  O LevelASArrays 2210 §8.2
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• Calling a procedure

  The main chart uses the subroutine symbol; the procedure gets its own chart tab.

  O LevelASSubroutines 2210 §8.1
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