Developing code

Worked examples (9)

• 1Write a first input-process-output program
• 2Identify the constants, variables, inputs and outputs of a task
• 3Diagnose a program that joins numbers instead of adding them
• 4Turn a pseudocode design into a running program
• 5Write a program with a constant, a subprogram and validation
• 6Explain the advantages of a high-level language
• 7Justify an incremental build strategy
• 8Evaluate the choice of language for a task
• 9Work a complete practical task from stem to saved file

Model answers (9)

• ✓Model answer — Edexcel 4CP0 Paper 1 style — short open-response
• ✓Model answer — Edexcel 4CP0 Paper 1 style — short open-response
• ✓Model answer — Edexcel 4CP0 Paper 1 style — short open-response
• ✓Model answer — Edexcel 4CP0 Paper 1 style — open-response
• ✓Model answer — Edexcel 4CP0 Paper 1 style — short open-response
• ✓Model answer — Edexcel 4CP0 Paper 1 style — open-response
• ✓Model answer — Edexcel 4CP0 Paper 2 style — practical task
• ✓Model answer — Edexcel 4CP0 Paper 1 style — open-response
• ✓Model answer — Edexcel 4CP0 Paper 1 style — extended open-response

Worked examples (9)

• 1State the techniques and say what each one achieves
• 2Improve the identifiers in a fragment
• 3Judge which comments are worth writing
• 4Explain how a piece of code works
• 5Diagnose a fault caused by indentation
• 6Rewrite a whole program for readability
• 7Analyse the effect of readability on maintenance
• 8Explain a fragment containing a nested structure
• 9Evaluate a claim about comments

Model answers (9)

• ✓Model answer — Edexcel 4CP0 Paper 1 style — short open-response
• ✓Model answer — Edexcel 4CP0 Paper 1 style — short open-response
• ✓Model answer — Edexcel 4CP0 Paper 1 style — short open-response
• ✓Model answer — Edexcel 4CP0 Paper 1 style — open-response
• ✓Model answer — Edexcel 4CP0 Paper 1 style — open-response
• ✓Model answer — Edexcel 4CP0 Paper 1 style — open-response
• ✓Model answer — Edexcel 4CP0 Paper 1 style — open-response
• ✓Model answer — Edexcel 4CP0 Paper 1 style — open-response
• ✓Model answer — Edexcel 4CP0 Paper 1 style — extended open-response

Worked examples (9)

• 1Classify three faults from their symptoms
• 2Find and correct a syntax error
• 3Interpret a NameError message
• 4Diagnose and repair an off-by-one IndexError
• 5Find a logic error hidden by operator precedence
• 6Trace a TypeError back to a line far above it
• 7Explain why logic errors are the hardest to detect
• 8Work the full identify-locate-fix-retest cycle on two errors
• 9Evaluate a claim about modern development tools

Model answers (9)

• ✓Model answer — Edexcel 4CP0 Paper 1 style — short open-response
• ✓Model answer — Edexcel 4CP0 Paper 1 style — short open-response
• ✓Model answer — Edexcel 4CP0 Paper 1 style — short open-response
• ✓Model answer — Edexcel 4CP0 Paper 1 style — open-response
• ✓Model answer — Edexcel 4CP0 Paper 1 style — open-response
• ✓Model answer — Edexcel 4CP0 Paper 1 style — open-response
• ✓Model answer — Edexcel 4CP0 Paper 1 style — open-response
• ✓Model answer — Edexcel 4CP0 Paper 1 style — open-response
• ✓Model answer — Edexcel 4CP0 Paper 1 style — extended open-response

Worked examples (9)

• 1Find a value after a variable is reassigned
• 2State a loop counter's value after the loop ends
• 3Identify which variables are in scope inside a procedure
• 4State a value at a named line on a named pass
• 5One variable, two points, two different answers
• 6Explain why a local counter is always 1
• 7Find an accumulator's value inside a nested loop
• 8Read the values at a paused breakpoint
• 9Track values before, during and after a procedure call

Model answers (9)

• ✓Model answer — Edexcel 4CP0 Paper 1 style — short open-response
• ✓Model answer — Edexcel 4CP0 Paper 1 style — short open-response
• ✓Model answer — Edexcel 4CP0 Paper 1 style — short open-response
• ✓Model answer — Edexcel 4CP0 Paper 1 style — open-response
• ✓Model answer — Edexcel 4CP0 Paper 1 style — open-response
• ✓Model answer — Edexcel 4CP0 Paper 1 style — open-response
• ✓Model answer — Edexcel 4CP0 Paper 2 style — task-based question
• ✓Model answer — Edexcel 4CP0 Paper 1 style — open-response
• ✓Model answer — Edexcel 4CP0 Paper 1 style — extended open-response

Worked examples (9)

• 1Classify three values as normal, boundary or erroneous
• 2Give one value of each type for a password rule
• 3Fill in the expected result column
• 4Choose the boundary value for a stated condition
• 5Design a three-row test plan for a PIN checker
• 6Find the boundaries of an array-processing program
• 7Plan tests for a program with two inputs
• 8Show that testing either side of the boundary is not enough
• 9Critique and improve someone else's test plan

Model answers (9)

• ✓Model answer — Edexcel 4CP0 Paper 1 style — short open-response
• ✓Model answer — Edexcel 4CP0 Paper 1 style — short open-response
• ✓Model answer — Edexcel 4CP0 Paper 1 style — short open-response
• ✓Model answer — Edexcel 4CP0 Paper 1 style — open-response
• ✓Model answer — Edexcel 4CP0 Paper 1 style — open-response
• ✓Model answer — Edexcel 4CP0 Paper 1 style — open-response
• ✓Model answer — Edexcel 4CP0 Paper 1 style — extended open-response
• ✓Model answer — Edexcel 4CP0 Paper 1 style — open-response
• ✓Model answer — Edexcel 4CP0 Paper 1 style — extended open-response

Worked examples (9)

• 1Identify one strength and one weakness
• 2Improve a magic number
• 3Sort five observations by criterion
• 4Evidence a robustness weakness and fix it
• 5Quantify an efficiency weakness
• 6Replace five variables with one array
• 7Evaluate a program against its requirements
• 8Show which requirements a program meets
• 9Assess which of two weaknesses matters more

Model answers (9)

• ✓Model answer — Edexcel 4CP0 Paper 1 style — short open-response
• ✓Model answer — Edexcel 4CP0 Paper 1 style — short open-response
• ✓Model answer — Edexcel 4CP0 Paper 1 style — short open-response
• ✓Model answer — Edexcel 4CP0 Paper 1 style — open-response
• ✓Model answer — Edexcel 4CP0 Paper 1 style — open-response
• ✓Model answer — Edexcel 4CP0 Paper 1 style — open-response
• ✓Model answer — Edexcel 4CP0 Paper 1 style — open-response
• ✓Model answer — Edexcel 4CP0 Paper 1 style — extended open-response
• ✓Model answer — Edexcel 4CP0 Paper 1 style — extended open-response