Code Patterns: Pseudocode, Python, SQL, CSS (Years 11 and 12)

Pseudocode keywords Code pattern

Keywords are in capitals; structural elements come in pairs (BEGIN/END, IF/ENDIF, WHILE/ENDWHILE); indent to show control structures.

Example: 'IF mark >= 50 THEN ... ENDIF'

Sequence Code pattern

Steps executed one after another in the order written.

Example: 'GET a; GET b; total = a + b'

Binary selection (IF THEN ELSE) Code pattern

IF condition THEN process ELSE other process ENDIF: one of two paths is taken.

Example: 'IF age >= 18 THEN DISPLAY "Adult" ELSE DISPLAY "Minor" ENDIF'

Multi-way selection (CASEWHERE) Code pattern

CASEWHERE expression evaluates to choice a: ... OTHERWISE: default END CASE; only one process runs.

Example: 'CASEWHERE grade evaluates to "A": ... OTHERWISE: ...'

Nested IF Code pattern

An IF inside the ELSE of another IF to test several conditions where only one process runs.

Example: 'IF a THEN ... ELSE IF b THEN ... ELSE ... ENDIF ENDIF'

WHILE loop (pre-test) Code pattern

WHILE condition is true ... ENDWHILE: the condition is tested before each loop, so the body may never run.

Example: 'WHILE count < 5 ... ENDWHILE'

REPEAT UNTIL loop (post-test) Code pattern

REPEAT ... UNTIL condition is true: the body runs at least once, then the condition is tested.

Example: 'REPEAT GET guess UNTIL guess = answer'

FOR / NEXT loop (counted) Code pattern

FOR variable = start TO finish STEP increment ... NEXT variable; used when the number of repeats is known.

Example: 'FOR i = 1 TO 5 ... NEXT i'

Check this one: Not found word-for-word in the supplied syllabus, specifications, marking guidelines or notes; the definition is standard computing knowledge, so check it against your class notes.

Subroutine and function (pseudocode) Code pattern

BEGIN name (parameters) ... END name. A function returns a single value with RETURN.

Example: 'BEGIN Add (x, y) total = x + y RETURN total END Add'

Array sum pattern Code pattern

Set total to 0, loop through every item adding it to the total, then display the total (initialise, loop, accumulate, output).

Example: 'total = 0; FOR each item: total = total + item'

Check this one: A coding pattern from the exam solution style, not a syllabus term.

Linear search pattern Code pattern

Check each item in order until found or the end is reached; set a Found flag, loop through and stop on a match.

Example: 'found = False; for i in list: if i == target: found = True'

Python input and output Code pattern

input() reads text from the user as a string; print() displays output; convert with int() or float().

Example: 'age = int(input("Age: "))'

Python selection (if elif else) Code pattern

if condition: ... elif condition: ... else: ...; indentation matters (Q19 marker note: indentation).

Example: 'if mark >= 50: print("Pass") else: print("Fail")'

Python for loop and range Code pattern

for i in range(start, stop): repeats; stop is exclusive; also loops over lists and strings.

Example: 'for i in range(1, 6): print(i)'

Python while loop Code pattern

while condition: ... repeats while True; make sure the condition changes.

Example: 'while guess != answer: guess = int(input())'

Python strings and slicing Code pattern

Strings are sequences: len(s), s[0], s[-1], s[1:4], s.upper(), s.lower(), s.split(), s.strip(), and ord()/chr() for character codes.

Example: 'word[0] is the first letter; word[-1] is the last.'

Python lists Code pattern

A list stores ordered items: append(), remove(), len(), sorting with sort(), looping, and 2D lists as a list of lists.

Example: 'grid = [[0]*3 for _ in range(3)]'

Python 2D list (grid) Code pattern

A list of lists addressed as grid[row][column]; loop with nested for loops.

Example: 'grid[1][2] = 5'

Python random numbers Code pattern

import random then random.randint(a, b) gives a whole number a to b inclusive; use a set or a check to avoid repeats.

Example: 'n = random.randint(1, 50)'

Check this one: Library use is allowed under 'modules and libraries'; random.randint is a standard Python function.

Python functions Code pattern

def name(parameters): ... return value. Functions must be defined before they are called (2025 Q19 marker note: call functions after definition).

Example: 'def area(w, h): return w * h'

Global and local variables Code pattern

A local variable exists only inside its function; a global variable is declared outside and can be used throughout (use the global keyword to change it inside a function).

Example: 'count = 0 (global); def add(): global count'

Python file handling Code pattern

open(filename, mode) with modes r (read), w (write, overwrites), a (append); use with to close the file automatically; read(), readline(), write().

Example: 'with open("data.txt") as f: lines = f.readlines()'

Python modules and libraries Code pattern

import a module to use its functions: import random, import math, from sklearn.linear_model import LinearRegression.

Example: 'import math'

Python classes and objects Code pattern

class Name: with __init__(self, ...) to set attributes; methods have self; create objects with Name(...); inheritance with class Child(Parent):.

Example: 'class Dog(Animal): def speak(self): return "Woof"'

Python validation function pattern Code pattern

Loop until the input is valid, using try/except for the conversion and if for range checks.

Example: 'while True: try: n = int(input()) ... except ValueError: ...'

Python try / except Code pattern

try: risky code except ValueError: handle the error; keeps the program running with a helpful message.

Example: 'except ValueError: print("Numbers only")'

Python sqlite3 parameterised query Code pattern

Use ? placeholders and pass values separately, never join user text into the SQL string, to stop SQL injection.

Example: 'cur.execute("SELECT * FROM user WHERE name = ?", (name,))'

Check this one: Parameterised queries are standard secure practice (defensive input handling); the syllabus does not name sqlite3.

Python file and ML code reading (scikit-learn) Code pattern

Know how to read: import, create the model, fit (train), predict.

Example: 'model.fit(x, y); model.predict([[4]])'

SQL statement structure Code pattern

SELECT fields FROM table WHERE criteria GROUP BY field ORDER BY field ASC or DESC; keyword AS renames a field for display.

Example: 'SELECT Name FROM Games WHERE Cost > 20 ORDER BY Name ASC'

SQL relational and logical operators Code pattern

Relational operators: CONTAINS, DOES NOT CONTAIN, EQUALS, NOT EQUAL TO, GREATER THAN (OR EQUAL TO), LESS THAN (OR EQUAL TO). Logical operators: AND, OR, NOT. Put text and dates in quotes.

Example: "WHERE Name CONTAINS 'war' AND Cost < 50"

SQL calculated aggregate with GROUP BY Code pattern

SELECT Developer, SUM(Cost) AS Totalcost FROM Games GROUP BY Developer ORDER BY Developer DESC.

Example: 'SUM (Games.cost) AS Totalcost'

CSS rule syntax Code pattern

selector { property: value; } with comments in /* */. h1 targets an element, #welcome targets an id, .red-text targets a class.

Example: '.red-text { color: red; }'

XSS JavaScript fragment reading Code pattern

Be able to read a short JavaScript fragment and spot where untrusted input is inserted into a page without sanitising.

Example: 'element.innerHTML = userInput is unsafe.'

Shell script pattern Code pattern

A script is a text file of commands run in order, e.g. mkdir site, cd site, touch index.html, cp, rm, cat, grep.

Example: 'mkdir site && cd site && touch index.html'