Mastering the Programming Language Subset

A program displays rainbow colours based on wavelength. Students must fix 10 different errors.

A program selects random exercises from an array. Multiple syntax and logic errors need fixing.

Completing the Random Number Line

The question asks to complete: index = random.

Check PLS page 13:

# PLS shows: random.randint(<a>, <b>)
# Returns random integer where a <= X <= b
# Array has 5 elements, indices 0-4

index = random.randint(0, 4)

Convert numbers 5-30 to letters A-Z using ASCII. Adding 60 to a number gives the ASCII code for the corresponding uppercase letter.

Task-by-Task Solution

# Task 1: Create integer variable (PLS page 5)
num = 0

# Task 2: Take input and convert to integer
# PLS page 5: int() and page 8: input()
num = int(input("Enter a number: "))

# Task 3: Check between 5 and 30
# PLS page 6: >= and <= operators, "and" operator
if num >= 5 and num <= 30:
    # Task 4: Add 60 and assign
    decimalCode = num + 60
    
    # Task 5: Join strings (PLS page 12: use +)
    letter = chr(decimalCode)
    message = str(num) + " is equal to " + letter
    print(message)
else:
    # Task 6: Display error message
    print("Invalid input")

Write coffee consumption data to a CSV file with 7 values per line (one week per line).

PLS Sections Needed

# Open file for writing - PLS page 8
outputFile = open("Q05_OUTPUT.TXT", "w")

# Process in groups of 7
for i in range(0, len(coffeeData), 7):
    # Build CSV line
    line = ""
    for j in range(7):
        line = line + str(coffeeData[i + j])
        if j < 6:
            line = line + ","
    
    # Add newline and write - PLS page 15 shows "\n"
    outputFile.write(line + "\n")

# Close file - PLS page 8
outputFile.close()

Read cow data from CSV, create unique keys, and store records in a table.

Key format: first 2 letters of breed + (tag ÷ 100) + first 2 letters of name

PLS Sections Needed

# Open file - PLS page 8
cowFile = open("Cows.txt", "r")
cowTable = []

# Read each line
for line in cowFile:
    # Remove whitespace - PLS page 11
    line = line.strip()
    
    # Split by comma - PLS page 11
    parts = line.split(",")
    name = parts[0]
    breed = parts[1]
    tag = int(parts[2])
    
    # Create key - PLS page 12 for slicing, page 6 for //
    key = breed[0:2] + str(tag // 100) + name[0:2]
    
    # Create record and append - PLS page 10
    record = [key, tag, name, breed]
    cowTable.append(record)

cowFile.close()
showTable()

Calculate the volume of a triangular prism with input validation and formatted output.

Key PLS References

Understanding Format Strings (PLS Page 12)

# Format: {:<alignment><width>.<precision><type>}
#
# {:8.2f} means:
#   8 = total width (8 characters)
#   .2 = 2 decimal places
#   f = fixed-point (decimal) number

layout = "{:8.2f}"
print("Volume:", layout.format(volume), "cubic units")

# Complete solution
base = float(input("Enter base: "))
height = float(input("Enter height: "))
length = float(input("Enter length: "))

# Validate all > 0 - PLS page 6
if base > 0 and height > 0 and length > 0:
    # Calculate area: A = 0.5 × b × h
    area = 0.5 * base * height
    print("Area:", round(area, 2))
    
    # Calculate volume: V = A × l
    volume = area * length
    
    # Formatted output - PLS page 12
    layout = "{:8.2f}"
    print("Volume:", layout.format(volume), "cubic units")
else:
    print("Invalid input")

print("Goodbye")

Calculate ingredient quantities for community events, rounding up to whole packs.

The math.ceil() Function

When you can't order partial bags or packs, use math.ceil() to round UP.

import math

adults = int(input("Enter number of adults: "))
children = int(input("Enter number of children: "))

# Calculate partial bags of crisps
# Adults: 0.75 bags, Children: 0.33 bags
partialBags = (adults * 0.75) + (children * 0.33)
print("Partial bags required:", partialBags)

# Round up to whole bags - PLS page 13
wholeBags = math.ceil(partialBags)
print("Order", wholeBags, "bags of crisps")

A menu-driven program with functions that return values and procedures that modify arrays.

PLS Page 8: Subprogram Syntax

def procname():
    # commands

def funcname():
    # commands
    return value

import random

pastaShapes = ["Fusilli", "Penne", "Spaghetti", "Farfalle"]

EXIT = 0
GET_SHAPE = 1
ADD_SHAPE = 2

def getChoice():
    # Function returns user's menu choice - PLS page 8
    choice = int(input("Enter option: "))
    return choice

def getShape():
    # Random index - PLS page 13: randint includes both endpoints
    index = random.randint(0, len(pastaShapes) - 1)
    return pastaShapes[index]

def addShape():
    # Append to list - PLS page 10
    newShape = input("Enter new pasta shape: ")
    pastaShapes.append(newShape)

# Main program
choice = -1
while choice != EXIT:
    print("1. Get random shape")
    print("2. Add new shape")
    print("0. Exit")
    
    choice = getChoice()
    
    if choice == GET_SHAPE:
        shape = getShape()
        print("Random shape:", shape)
    elif choice == ADD_SHAPE:
        addShape()
    elif choice != EXIT:
        print("Invalid option")

Generate user IDs using string manipulation and ASCII values.

Understanding ord() vs int()

# For user "Viola Bassir" born 15/06/2005
# ID = "bassirv" + sum of ASCII values of "15062005"

# Calculate number part using ord() - PLS page 9
dob = "15062005"
total = 0
for char in dob:
    total = total + ord(char)
    # ord("1")=49, ord("5")=53, ord("0")=48...

# total = 49+53+48+54+50+48+48+53 = 403
# Final ID: "bassirv403"