Additional programming techniques: The use of records to store data

The idea

A record groups related data items about one entity into a single structure. Each field has a name and a data type, such as a student record with fields name (string), age (integer) and average (real). In Python you can implement a record as a dictionary with named keys, for example student = {'name':'Ama','age':14,'average':67.5}. Access a field with student['name'] and update it with student['age'] = 15. Records make programs clearer because fields are referenced by name rather than by position, and they keep related values together. You can store many records in a list or file, then loop through them to search, calculate or display. When reading records from a file, split each line into fields and convert numeric fields before use.

What earns the marks

• A record is a data structure that stores related fields about one entity, with each field having a name and a data type.
• Fields are accessed by name, which improves readability and reduces errors compared with remembering positional indexes.
• Records can be implemented in Python using dictionaries with string keys, or as objects of a class with attributes.
• Multiple records can be held in a list, allowing iteration to search, sort, total or display data for many entities.
• When records are stored in a text file, each line can represent one record and delimiters such as commas separate fields; parsing and type conversion are needed after reading.
• Updating a record means assigning a new value to a named field, for example student['age'] = 15, without affecting other fields.

Common mistakes and how to put them right

• Confusing a record with an array, then accessing fields by numeric index.

  Put it right: Use named keys or attributes so the meaning of each field is clear.

• Storing numeric data as strings and then attempting arithmetic.

  Put it right: Convert fields with int() or float() after reading or input.

• Forgetting that a dictionary key must match exactly, including case.

  Put it right: Use consistent key names and check spelling.

• Treating a list of records as a single record.

  Put it right: Loop over the list and access fields on each record in turn.

Exam tips

• Define the fields and their data types before writing code, so your record structure is complete and consistent.
• Use meaningful field names such as 'price' or 'quantity' rather than vague names like 'x' or 'data'.
• When reading records from a file, show how you split each line and convert numeric fields before calculation.
• If asked to update a record, show the assignment to the named field and explain that other fields remain unchanged.