Paper 2: Writing Programs from Given Specifications

One of the most challenging question types in OCR J277 Paper 2 asks you to write a program (or section of code) based on a given specification. These questions typically carry 4-8 marks and test your ability to translate a problem description into working code.

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Approaching a Program-Writing Question

Follow this systematic approach:

Step 1: Read and Annotate (1 minute)

• Read the specification twice
• Underline key requirements: inputs, processing, outputs, validation
• Identify any constraints (e.g., "must use a loop", "must use a function")

Step 2: Plan Your Structure (1-2 minutes)

• What variables do you need?
• What data types will they be?
• What control structures are needed (if, for, while)?
• Do you need any subprograms (functions/procedures)?

Step 3: Write the Code (main time)

• Write clean, indented code
• Use meaningful variable names
• Follow the specification exactly — do not add extra features
• Include any required validation or error handling

Step 4: Check (30 seconds)

• Mentally trace through with a sample input
• Check you have addressed every requirement in the specification

OCR Exam Tip: You can use either OCR pseudocode or Python. The mark scheme accepts both. Choose whichever you are more comfortable with, but be consistent within your answer.

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Common Program Specifications

Pattern 1: Input Validation

Specification: Ask the user to enter a number between 1 and 100. Keep asking until a valid number is entered.

// OCR pseudocode
do
    num = int(input("Enter a number between 1 and 100: "))
until num >= 1 AND num <= 100
print("You entered: " + str(num))

# Python
num = int(input("Enter a number between 1 and 100: "))
while num < 1 or num > 100:
    num = int(input("Enter a number between 1 and 100: "))
print("You entered:", num)

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Pattern 2: Counting and Totalling

Specification: Ask the user to enter 10 test scores. Calculate and display the total and average.

// OCR pseudocode
total = 0
for i = 1 to 10
    score = int(input("Enter score: "))
    total = total + score
next i
average = total / 10
print("Total: " + str(total))
print("Average: " + str(average))

# Python
total = 0
for i in range(10):
    score = int(input("Enter score: "))
    total += score
average = total / 10
print("Total:", total)
print("Average:", average)

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Pattern 3: Searching an Array

Specification: Search an array of names for a given name and report whether it was found.